what are limitations of research studies

How to Write Limitations of the Study (with examples)

This blog emphasizes the importance of recognizing and effectively writing about limitations in research. It discusses the types of limitations, their significance, and provides guidelines for writing about them, highlighting their role in advancing scholarly research.

Updated on August 24, 2023

No matter how well thought out, every research endeavor encounters challenges. There is simply no way to predict all possible variances throughout the process.

These uncharted boundaries and abrupt constraints are known as limitations in research . Identifying and acknowledging limitations is crucial for conducting rigorous studies. Limitations provide context and shed light on gaps in the prevailing inquiry and literature.

This article explores the importance of recognizing limitations and discusses how to write them effectively. By interpreting limitations in research and considering prevalent examples, we aim to reframe the perception from shameful mistakes to respectable revelations.

What are limitations in research?

In the clearest terms, research limitations are the practical or theoretical shortcomings of a study that are often outside of the researcher’s control . While these weaknesses limit the generalizability of a study’s conclusions, they also present a foundation for future research.

Sometimes limitations arise from tangible circumstances like time and funding constraints, or equipment and participant availability. Other times the rationale is more obscure and buried within the research design. Common types of limitations and their ramifications include:

• Theoretical: limits the scope, depth, or applicability of a study.
• Methodological: limits the quality, quantity, or diversity of the data.
• Empirical: limits the representativeness, validity, or reliability of the data.
• Analytical: limits the accuracy, completeness, or significance of the findings.
• Ethical: limits the access, consent, or confidentiality of the data.

Regardless of how, when, or why they arise, limitations are a natural part of the research process and should never be ignored . Like all other aspects, they are vital in their own purpose.

Why is identifying limitations important?

Whether to seek acceptance or avoid struggle, humans often instinctively hide flaws and mistakes. Merging this thought process into research by attempting to hide limitations, however, is a bad idea. It has the potential to negate the validity of outcomes and damage the reputation of scholars.

By identifying and addressing limitations throughout a project, researchers strengthen their arguments and curtail the chance of peer censure based on overlooked mistakes. Pointing out these flaws shows an understanding of variable limits and a scrupulous research process.

Showing awareness of and taking responsibility for a project’s boundaries and challenges validates the integrity and transparency of a researcher. It further demonstrates the researchers understand the applicable literature and have thoroughly evaluated their chosen research methods.

Presenting limitations also benefits the readers by providing context for research findings. It guides them to interpret the project’s conclusions only within the scope of very specific conditions. By allowing for an appropriate generalization of the findings that is accurately confined by research boundaries and is not too broad, limitations boost a study’s credibility .

Limitations are true assets to the research process. They highlight opportunities for future research. When researchers identify the limitations of their particular approach to a study question, they enable precise transferability and improve chances for reproducibility. 

Simply stating a project’s limitations is not adequate for spurring further research, though. To spark the interest of other researchers, these acknowledgements must come with thorough explanations regarding how the limitations affected the current study and how they can potentially be overcome with amended methods.

How to write limitations

Typically, the information about a study’s limitations is situated either at the beginning of the discussion section to provide context for readers or at the conclusion of the discussion section to acknowledge the need for further research. However, it varies depending upon the target journal or publication guidelines. 

Don’t hide your limitations

It is also important to not bury a limitation in the body of the paper unless it has a unique connection to a topic in that section. If so, it needs to be reiterated with the other limitations or at the conclusion of the discussion section. Wherever it is included in the manuscript, ensure that the limitations section is prominently positioned and clearly introduced.

While maintaining transparency by disclosing limitations means taking a comprehensive approach, it is not necessary to discuss everything that could have potentially gone wrong during the research study. If there is no commitment to investigation in the introduction, it is unnecessary to consider the issue a limitation to the research. Wholly consider the term ‘limitations’ and ask, “Did it significantly change or limit the possible outcomes?” Then, qualify the occurrence as either a limitation to include in the current manuscript or as an idea to note for other projects. 

Writing limitations

Once the limitations are concretely identified and it is decided where they will be included in the paper, researchers are ready for the writing task. Including only what is pertinent, keeping explanations detailed but concise, and employing the following guidelines is key for crafting valuable limitations:

1) Identify and describe the limitations : Clearly introduce the limitation by classifying its form and specifying its origin. For example:

• An unintentional bias encountered during data collection
• An intentional use of unplanned post-hoc data analysis

2) Explain the implications : Describe how the limitation potentially influences the study’s findings and how the validity and generalizability are subsequently impacted. Provide examples and evidence to support claims of the limitations’ effects without making excuses or exaggerating their impact. Overall, be transparent and objective in presenting the limitations, without undermining the significance of the research. 

3) Provide alternative approaches for future studies : Offer specific suggestions for potential improvements or avenues for further investigation. Demonstrate a proactive approach by encouraging future research that addresses the identified gaps and, therefore, expands the knowledge base.

Whether presenting limitations as an individual section within the manuscript or as a subtopic in the discussion area, authors should use clear headings and straightforward language to facilitate readability. There is no need to complicate limitations with jargon, computations, or complex datasets.

Examples of common limitations

Limitations are generally grouped into two categories , methodology and research process .

Methodology limitations

Methodology may include limitations due to:

• Sample size
• Lack of available or reliable data
• Lack of prior research studies on the topic
• Measure used to collect the data
• Self-reported data

The researcher is addressing how the large sample size requires a reassessment of the measures used to collect and analyze the data.

Research process limitations

Limitations during the research process may arise from:

• Access to information
• Longitudinal effects
• Cultural and other biases
• Language fluency
• Time constraints

The author is pointing out that the model’s estimates are based on potentially biased observational studies.

Final thoughts

Successfully proving theories and touting great achievements are only two very narrow goals of scholarly research. The true passion and greatest efforts of researchers comes more in the form of confronting assumptions and exploring the obscure.

In many ways, recognizing and sharing the limitations of a research study both allows for and encourages this type of discovery that continuously pushes research forward. By using limitations to provide a transparent account of the project's boundaries and to contextualize the findings, researchers pave the way for even more robust and impactful research in the future.

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Home » Limitations in Research – Types, Examples and Writing Guide

Limitations in Research – Types, Examples and Writing Guide

Table of Contents

Limitations in Research

Limitations in research refer to the factors that may affect the results, conclusions , and generalizability of a study. These limitations can arise from various sources, such as the design of the study, the sampling methods used, the measurement tools employed, and the limitations of the data analysis techniques.

Types of Limitations in Research

Types of Limitations in Research are as follows:

Sample Size Limitations

This refers to the size of the group of people or subjects that are being studied. If the sample size is too small, then the results may not be representative of the population being studied. This can lead to a lack of generalizability of the results.

Time Limitations

Time limitations can be a constraint on the research process . This could mean that the study is unable to be conducted for a long enough period of time to observe the long-term effects of an intervention, or to collect enough data to draw accurate conclusions.

Selection Bias

This refers to a type of bias that can occur when the selection of participants in a study is not random. This can lead to a biased sample that is not representative of the population being studied.

Confounding Variables

Confounding variables are factors that can influence the outcome of a study, but are not being measured or controlled for. These can lead to inaccurate conclusions or a lack of clarity in the results.

Measurement Error

This refers to inaccuracies in the measurement of variables, such as using a faulty instrument or scale. This can lead to inaccurate results or a lack of validity in the study.

Ethical Limitations

Ethical limitations refer to the ethical constraints placed on research studies. For example, certain studies may not be allowed to be conducted due to ethical concerns, such as studies that involve harm to participants.

Examples of Limitations in Research

Some Examples of Limitations in Research are as follows:

Research Title: “The Effectiveness of Machine Learning Algorithms in Predicting Customer Behavior”

Limitations:

• The study only considered a limited number of machine learning algorithms and did not explore the effectiveness of other algorithms.
• The study used a specific dataset, which may not be representative of all customer behaviors or demographics.
• The study did not consider the potential ethical implications of using machine learning algorithms in predicting customer behavior.

Research Title: “The Impact of Online Learning on Student Performance in Computer Science Courses”

• The study was conducted during the COVID-19 pandemic, which may have affected the results due to the unique circumstances of remote learning.
• The study only included students from a single university, which may limit the generalizability of the findings to other institutions.
• The study did not consider the impact of individual differences, such as prior knowledge or motivation, on student performance in online learning environments.

Research Title: “The Effect of Gamification on User Engagement in Mobile Health Applications”

• The study only tested a specific gamification strategy and did not explore the effectiveness of other gamification techniques.
• The study relied on self-reported measures of user engagement, which may be subject to social desirability bias or measurement errors.
• The study only included a specific demographic group (e.g., young adults) and may not be generalizable to other populations with different preferences or needs.

How to Write Limitations in Research

When writing about the limitations of a research study, it is important to be honest and clear about the potential weaknesses of your work. Here are some tips for writing about limitations in research:

• Identify the limitations: Start by identifying the potential limitations of your research. These may include sample size, selection bias, measurement error, or other issues that could affect the validity and reliability of your findings.
• Be honest and objective: When describing the limitations of your research, be honest and objective. Do not try to minimize or downplay the limitations, but also do not exaggerate them. Be clear and concise in your description of the limitations.
• Provide context: It is important to provide context for the limitations of your research. For example, if your sample size was small, explain why this was the case and how it may have affected your results. Providing context can help readers understand the limitations in a broader context.
• Discuss implications : Discuss the implications of the limitations for your research findings. For example, if there was a selection bias in your sample, explain how this may have affected the generalizability of your findings. This can help readers understand the limitations in terms of their impact on the overall validity of your research.
• Provide suggestions for future research : Finally, provide suggestions for future research that can address the limitations of your study. This can help readers understand how your research fits into the broader field and can provide a roadmap for future studies.

Purpose of Limitations in Research

There are several purposes of limitations in research. Here are some of the most important ones:

• To acknowledge the boundaries of the study : Limitations help to define the scope of the research project and set realistic expectations for the findings. They can help to clarify what the study is not intended to address.
• To identify potential sources of bias: Limitations can help researchers identify potential sources of bias in their research design, data collection, or analysis. This can help to improve the validity and reliability of the findings.
• To provide opportunities for future research: Limitations can highlight areas for future research and suggest avenues for further exploration. This can help to advance knowledge in a particular field.
• To demonstrate transparency and accountability: By acknowledging the limitations of their research, researchers can demonstrate transparency and accountability to their readers, peers, and funders. This can help to build trust and credibility in the research community.
• To encourage critical thinking: Limitations can encourage readers to critically evaluate the study’s findings and consider alternative explanations or interpretations. This can help to promote a more nuanced and sophisticated understanding of the topic under investigation.

When to Write Limitations in Research

Limitations should be included in research when they help to provide a more complete understanding of the study’s results and implications. A limitation is any factor that could potentially impact the accuracy, reliability, or generalizability of the study’s findings.

It is important to identify and discuss limitations in research because doing so helps to ensure that the results are interpreted appropriately and that any conclusions drawn are supported by the available evidence. Limitations can also suggest areas for future research, highlight potential biases or confounding factors that may have affected the results, and provide context for the study’s findings.

Generally, limitations should be discussed in the conclusion section of a research paper or thesis, although they may also be mentioned in other sections, such as the introduction or methods. The specific limitations that are discussed will depend on the nature of the study, the research question being investigated, and the data that was collected.

Examples of limitations that might be discussed in research include sample size limitations, data collection methods, the validity and reliability of measures used, and potential biases or confounding factors that could have affected the results. It is important to note that limitations should not be used as a justification for poor research design or methodology, but rather as a way to enhance the understanding and interpretation of the study’s findings.

Importance of Limitations in Research

Here are some reasons why limitations are important in research:

• Enhances the credibility of research: Limitations highlight the potential weaknesses and threats to validity, which helps readers to understand the scope and boundaries of the study. This improves the credibility of research by acknowledging its limitations and providing a clear picture of what can and cannot be concluded from the study.
• Facilitates replication: By highlighting the limitations, researchers can provide detailed information about the study’s methodology, data collection, and analysis. This information helps other researchers to replicate the study and test the validity of the findings, which enhances the reliability of research.
• Guides future research : Limitations provide insights into areas for future research by identifying gaps or areas that require further investigation. This can help researchers to design more comprehensive and effective studies that build on existing knowledge.
• Provides a balanced view: Limitations help to provide a balanced view of the research by highlighting both strengths and weaknesses. This ensures that readers have a clear understanding of the study’s limitations and can make informed decisions about the generalizability and applicability of the findings.

Advantages of Limitations in Research

Here are some potential advantages of limitations in research:

• Focus : Limitations can help researchers focus their study on a specific area or population, which can make the research more relevant and useful.
• Realism : Limitations can make a study more realistic by reflecting the practical constraints and challenges of conducting research in the real world.
• Innovation : Limitations can spur researchers to be more innovative and creative in their research design and methodology, as they search for ways to work around the limitations.
• Rigor : Limitations can actually increase the rigor and credibility of a study, as researchers are forced to carefully consider the potential sources of bias and error, and address them to the best of their abilities.
• Generalizability : Limitations can actually improve the generalizability of a study by ensuring that it is not overly focused on a specific sample or situation, and that the results can be applied more broadly.

About the author

Muhammad Hassan

Researcher, Academic Writer, Web developer

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The limitations of the study are those characteristics of design or methodology that impacted or influenced the interpretation of the findings from your research. Study limitations are the constraints placed on the ability to generalize from the results, to further describe applications to practice, and/or related to the utility of findings that are the result of the ways in which you initially chose to design the study or the method used to establish internal and external validity or the result of unanticipated challenges that emerged during the study.

Price, James H. and Judy Murnan. “Research Limitations and the Necessity of Reporting Them.” American Journal of Health Education 35 (2004): 66-67; Theofanidis, Dimitrios and Antigoni Fountouki. "Limitations and Delimitations in the Research Process." Perioperative Nursing 7 (September-December 2018): 155-163. .

Importance of...

Always acknowledge a study's limitations. It is far better that you identify and acknowledge your study’s limitations than to have them pointed out by your professor and have your grade lowered because you appeared to have ignored them or didn't realize they existed.

Keep in mind that acknowledgment of a study's limitations is an opportunity to make suggestions for further research. If you do connect your study's limitations to suggestions for further research, be sure to explain the ways in which these unanswered questions may become more focused because of your study.

Acknowledgment of a study's limitations also provides you with opportunities to demonstrate that you have thought critically about the research problem, understood the relevant literature published about it, and correctly assessed the methods chosen for studying the problem. A key objective of the research process is not only discovering new knowledge but also to confront assumptions and explore what we don't know.

Claiming limitations is a subjective process because you must evaluate the impact of those limitations . Don't just list key weaknesses and the magnitude of a study's limitations. To do so diminishes the validity of your research because it leaves the reader wondering whether, or in what ways, limitation(s) in your study may have impacted the results and conclusions. Limitations require a critical, overall appraisal and interpretation of their impact. You should answer the question: do these problems with errors, methods, validity, etc. eventually matter and, if so, to what extent?

Price, James H. and Judy Murnan. “Research Limitations and the Necessity of Reporting Them.” American Journal of Health Education 35 (2004): 66-67; Structure: How to Structure the Research Limitations Section of Your Dissertation. Dissertations and Theses: An Online Textbook. Laerd.com.

Descriptions of Possible Limitations

All studies have limitations . However, it is important that you restrict your discussion to limitations related to the research problem under investigation. For example, if a meta-analysis of existing literature is not a stated purpose of your research, it should not be discussed as a limitation. Do not apologize for not addressing issues that you did not promise to investigate in the introduction of your paper.

Here are examples of limitations related to methodology and the research process you may need to describe and discuss how they possibly impacted your results. Note that descriptions of limitations should be stated in the past tense because they were discovered after you completed your research.

Possible Methodological Limitations

• Sample size -- the number of the units of analysis you use in your study is dictated by the type of research problem you are investigating. Note that, if your sample size is too small, it will be difficult to find significant relationships from the data, as statistical tests normally require a larger sample size to ensure a representative distribution of the population and to be considered representative of groups of people to whom results will be generalized or transferred. Note that sample size is generally less relevant in qualitative research if explained in the context of the research problem.
• Lack of available and/or reliable data -- a lack of data or of reliable data will likely require you to limit the scope of your analysis, the size of your sample, or it can be a significant obstacle in finding a trend and a meaningful relationship. You need to not only describe these limitations but provide cogent reasons why you believe data is missing or is unreliable. However, don’t just throw up your hands in frustration; use this as an opportunity to describe a need for future research based on designing a different method for gathering data.
• Lack of prior research studies on the topic -- citing prior research studies forms the basis of your literature review and helps lay a foundation for understanding the research problem you are investigating. Depending on the currency or scope of your research topic, there may be little, if any, prior research on your topic. Before assuming this to be true, though, consult with a librarian! In cases when a librarian has confirmed that there is little or no prior research, you may be required to develop an entirely new research typology [for example, using an exploratory rather than an explanatory research design ]. Note again that discovering a limitation can serve as an important opportunity to identify new gaps in the literature and to describe the need for further research.
• Measure used to collect the data -- sometimes it is the case that, after completing your interpretation of the findings, you discover that the way in which you gathered data inhibited your ability to conduct a thorough analysis of the results. For example, you regret not including a specific question in a survey that, in retrospect, could have helped address a particular issue that emerged later in the study. Acknowledge the deficiency by stating a need for future researchers to revise the specific method for gathering data.
• Self-reported data -- whether you are relying on pre-existing data or you are conducting a qualitative research study and gathering the data yourself, self-reported data is limited by the fact that it rarely can be independently verified. In other words, you have to the accuracy of what people say, whether in interviews, focus groups, or on questionnaires, at face value. However, self-reported data can contain several potential sources of bias that you should be alert to and note as limitations. These biases become apparent if they are incongruent with data from other sources. These are: (1) selective memory [remembering or not remembering experiences or events that occurred at some point in the past]; (2) telescoping [recalling events that occurred at one time as if they occurred at another time]; (3) attribution [the act of attributing positive events and outcomes to one's own agency, but attributing negative events and outcomes to external forces]; and, (4) exaggeration [the act of representing outcomes or embellishing events as more significant than is actually suggested from other data].

Possible Limitations of the Researcher

• Access -- if your study depends on having access to people, organizations, data, or documents and, for whatever reason, access is denied or limited in some way, the reasons for this needs to be described. Also, include an explanation why being denied or limited access did not prevent you from following through on your study.
• Longitudinal effects -- unlike your professor, who can literally devote years [even a lifetime] to studying a single topic, the time available to investigate a research problem and to measure change or stability over time is constrained by the due date of your assignment. Be sure to choose a research problem that does not require an excessive amount of time to complete the literature review, apply the methodology, and gather and interpret the results. If you're unsure whether you can complete your research within the confines of the assignment's due date, talk to your professor.
• Cultural and other type of bias -- we all have biases, whether we are conscience of them or not. Bias is when a person, place, event, or thing is viewed or shown in a consistently inaccurate way. Bias is usually negative, though one can have a positive bias as well, especially if that bias reflects your reliance on research that only support your hypothesis. When proof-reading your paper, be especially critical in reviewing how you have stated a problem, selected the data to be studied, what may have been omitted, the manner in which you have ordered events, people, or places, how you have chosen to represent a person, place, or thing, to name a phenomenon, or to use possible words with a positive or negative connotation. NOTE :   If you detect bias in prior research, it must be acknowledged and you should explain what measures were taken to avoid perpetuating that bias. For example, if a previous study only used boys to examine how music education supports effective math skills, describe how your research expands the study to include girls.
• Fluency in a language -- if your research focuses , for example, on measuring the perceived value of after-school tutoring among Mexican-American ESL [English as a Second Language] students and you are not fluent in Spanish, you are limited in being able to read and interpret Spanish language research studies on the topic or to speak with these students in their primary language. This deficiency should be acknowledged.

Aguinis, Hermam and Jeffrey R. Edwards. “Methodological Wishes for the Next Decade and How to Make Wishes Come True.” Journal of Management Studies 51 (January 2014): 143-174; Brutus, Stéphane et al. "Self-Reported Limitations and Future Directions in Scholarly Reports: Analysis and Recommendations." Journal of Management 39 (January 2013): 48-75; Senunyeme, Emmanuel K. Business Research Methods. Powerpoint Presentation. Regent University of Science and Technology; ter Riet, Gerben et al. “All That Glitters Isn't Gold: A Survey on Acknowledgment of Limitations in Biomedical Studies.” PLOS One 8 (November 2013): 1-6.

Structure and Writing Style

Information about the limitations of your study are generally placed either at the beginning of the discussion section of your paper so the reader knows and understands the limitations before reading the rest of your analysis of the findings, or, the limitations are outlined at the conclusion of the discussion section as an acknowledgement of the need for further study. Statements about a study's limitations should not be buried in the body [middle] of the discussion section unless a limitation is specific to something covered in that part of the paper. If this is the case, though, the limitation should be reiterated at the conclusion of the section.

If you determine that your study is seriously flawed due to important limitations , such as, an inability to acquire critical data, consider reframing it as an exploratory study intended to lay the groundwork for a more complete research study in the future. Be sure, though, to specifically explain the ways that these flaws can be successfully overcome in a new study.

But, do not use this as an excuse for not developing a thorough research paper! Review the tab in this guide for developing a research topic . If serious limitations exist, it generally indicates a likelihood that your research problem is too narrowly defined or that the issue or event under study is too recent and, thus, very little research has been written about it. If serious limitations do emerge, consult with your professor about possible ways to overcome them or how to revise your study.

When discussing the limitations of your research, be sure to:

• Describe each limitation in detailed but concise terms;
• Explain why each limitation exists;
• Provide the reasons why each limitation could not be overcome using the method(s) chosen to acquire or gather the data [cite to other studies that had similar problems when possible];
• Assess the impact of each limitation in relation to the overall findings and conclusions of your study; and,
• If appropriate, describe how these limitations could point to the need for further research.

Remember that the method you chose may be the source of a significant limitation that has emerged during your interpretation of the results [for example, you didn't interview a group of people that you later wish you had]. If this is the case, don't panic. Acknowledge it, and explain how applying a different or more robust methodology might address the research problem more effectively in a future study. A underlying goal of scholarly research is not only to show what works, but to demonstrate what doesn't work or what needs further clarification.

Aguinis, Hermam and Jeffrey R. Edwards. “Methodological Wishes for the Next Decade and How to Make Wishes Come True.” Journal of Management Studies 51 (January 2014): 143-174; Brutus, Stéphane et al. "Self-Reported Limitations and Future Directions in Scholarly Reports: Analysis and Recommendations." Journal of Management 39 (January 2013): 48-75; Ioannidis, John P.A. "Limitations are not Properly Acknowledged in the Scientific Literature." Journal of Clinical Epidemiology 60 (2007): 324-329; Pasek, Josh. Writing the Empirical Social Science Research Paper: A Guide for the Perplexed. January 24, 2012. Academia.edu; Structure: How to Structure the Research Limitations Section of Your Dissertation. Dissertations and Theses: An Online Textbook. Laerd.com; What Is an Academic Paper? Institute for Writing Rhetoric. Dartmouth College; Writing the Experimental Report: Methods, Results, and Discussion. The Writing Lab and The OWL. Purdue University.

Writing Tip

Don't Inflate the Importance of Your Findings!

After all the hard work and long hours devoted to writing your research paper, it is easy to get carried away with attributing unwarranted importance to what you’ve done. We all want our academic work to be viewed as excellent and worthy of a good grade, but it is important that you understand and openly acknowledge the limitations of your study. Inflating the importance of your study's findings could be perceived by your readers as an attempt hide its flaws or encourage a biased interpretation of the results. A small measure of humility goes a long way!

Another Writing Tip

Negative Results are Not a Limitation!

Negative evidence refers to findings that unexpectedly challenge rather than support your hypothesis. If you didn't get the results you anticipated, it may mean your hypothesis was incorrect and needs to be reformulated. Or, perhaps you have stumbled onto something unexpected that warrants further study. Moreover, the absence of an effect may be very telling in many situations, particularly in experimental research designs. In any case, your results may very well be of importance to others even though they did not support your hypothesis. Do not fall into the trap of thinking that results contrary to what you expected is a limitation to your study. If you carried out the research well, they are simply your results and only require additional interpretation.

Lewis, George H. and Jonathan F. Lewis. “The Dog in the Night-Time: Negative Evidence in Social Research.” The British Journal of Sociology 31 (December 1980): 544-558.

Yet Another Writing Tip

Sample Size Limitations in Qualitative Research

Sample sizes are typically smaller in qualitative research because, as the study goes on, acquiring more data does not necessarily lead to more information. This is because one occurrence of a piece of data, or a code, is all that is necessary to ensure that it becomes part of the analysis framework. However, it remains true that sample sizes that are too small cannot adequately support claims of having achieved valid conclusions and sample sizes that are too large do not permit the deep, naturalistic, and inductive analysis that defines qualitative inquiry. Determining adequate sample size in qualitative research is ultimately a matter of judgment and experience in evaluating the quality of the information collected against the uses to which it will be applied and the particular research method and purposeful sampling strategy employed. If the sample size is found to be a limitation, it may reflect your judgment about the methodological technique chosen [e.g., single life history study versus focus group interviews] rather than the number of respondents used.

Boddy, Clive Roland. "Sample Size for Qualitative Research." Qualitative Market Research: An International Journal 19 (2016): 426-432; Huberman, A. Michael and Matthew B. Miles. "Data Management and Analysis Methods." In Handbook of Qualitative Research . Norman K. Denzin and Yvonna S. Lincoln, eds. (Thousand Oaks, CA: Sage, 1994), pp. 428-444; Blaikie, Norman. "Confounding Issues Related to Determining Sample Size in Qualitative Research." International Journal of Social Research Methodology 21 (2018): 635-641; Oppong, Steward Harrison. "The Problem of Sampling in qualitative Research." Asian Journal of Management Sciences and Education 2 (2013): 202-210.

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How to present limitations in research

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Limitations don’t invalidate or diminish your results, but it’s best to acknowledge them. This will enable you to address any questions your study failed to answer because of them.

In this guide, learn how to recognize, present, and overcome limitations in research.

• What is a research limitation?

Research limitations are weaknesses in your research design or execution that may have impacted outcomes and conclusions. Uncovering limitations doesn’t necessarily indicate poor research design—it just means you encountered challenges you couldn’t have anticipated that limited your research efforts.

Does basic research have limitations?

Basic research aims to provide more information about your research topic . It requires the same standard research methodology and data collection efforts as any other research type, and it can also have limitations.

• Common research limitations

Researchers encounter common limitations when embarking on a study. Limitations can occur in relation to the methods you apply or the research process you design. They could also be connected to you as the researcher.

Methodology limitations

Not having access to data or reliable information can impact the methods used to facilitate your research. A lack of data or reliability may limit the parameters of your study area and the extent of your exploration.

Your sample size may also be affected because you won’t have any direction on how big or small it should be and who or what you should include. Having too few participants won’t adequately represent the population or groups of people needed to draw meaningful conclusions.

Research process limitations

The study’s design can impose constraints on the process. For example, as you’re conducting the research, issues may arise that don’t conform to the data collection methodology you developed. You may not realize until well into the process that you should have incorporated more specific questions or comprehensive experiments to generate the data you need to have confidence in your results.

Constraints on resources can also have an impact. Being limited on participants or participation incentives may limit your sample sizes. Insufficient tools, equipment, and materials to conduct a thorough study may also be a factor.

Common researcher limitations

Here are some of the common researcher limitations you may encounter:

Time: some research areas require multi-year longitudinal approaches, but you might not be able to dedicate that much time. Imagine you want to measure how much memory a person loses as they age. This may involve conducting multiple tests on a sample of participants over 20–30 years, which may be impossible.

Bias: researchers can consciously or unconsciously apply bias to their research. Biases can contribute to relying on research sources and methodologies that will only support your beliefs about the research you’re embarking on. You might also omit relevant issues or participants from the scope of your study because of your biases.

Limited access to data : you may need to pay to access specific databases or journals that would be helpful to your research process. You might also need to gain information from certain people or organizations but have limited access to them. These cases require readjusting your process and explaining why your findings are still reliable.

• Why is it important to identify limitations?

Identifying limitations adds credibility to research and provides a deeper understanding of how you arrived at your conclusions.

Constraints may have prevented you from collecting specific data or information you hoped would prove or disprove your hypothesis or provide a more comprehensive understanding of your research topic.

However, identifying the limitations contributing to your conclusions can inspire further research efforts that help gather more substantial information and data.

• Where to put limitations in a research paper

A research paper is broken up into different sections that appear in the following order:

Introduction

Methodology

The discussion portion of your paper explores your findings and puts them in the context of the overall research. Either place research limitations at the beginning of the discussion section before the analysis of your findings or at the end of the section to indicate that further research needs to be pursued.

What not to include in the limitations section

Evidence that doesn’t support your hypothesis is not a limitation, so you shouldn’t include it in the limitation section. Don’t just list limitations and their degree of severity without further explanation.

• How to present limitations

You’ll want to present the limitations of your study in a way that doesn’t diminish the validity of your research and leave the reader wondering if your results and conclusions have been compromised.

Include only the limitations that directly relate to and impact how you addressed your research questions. Following a specific format enables the reader to develop an understanding of the weaknesses within the context of your findings without doubting the quality and integrity of your research.

Identify the limitations specific to your study

You don’t have to identify every possible limitation that might have occurred during your research process. Only identify those that may have influenced the quality of your findings and your ability to answer your research question.

Explain study limitations in detail

This explanation should be the most significant portion of your limitation section.

Link each limitation with an interpretation and appraisal of their impact on the study. You’ll have to evaluate and explain whether the error, method, or validity issues influenced the study’s outcome and how.

Propose a direction for future studies and present alternatives

In this section, suggest how researchers can avoid the pitfalls you experienced during your research process.

If an issue with methodology was a limitation, propose alternate methods that may help with a smoother and more conclusive research project . Discuss the pros and cons of your alternate recommendation.

Describe steps taken to minimize each limitation

You probably took steps to try to address or mitigate limitations when you noticed them throughout the course of your research project. Describe these steps in the limitation section.

• Limitation example

“Approaches like stem cell transplantation and vaccination in AD [Alzheimer’s disease] work on a cellular or molecular level in the laboratory. However, translation into clinical settings will remain a challenge for the next decade.”

The authors are saying that even though these methods showed promise in helping people with memory loss when conducted in the lab (in other words, using animal studies), more studies are needed. These may be controlled clinical trials, for example. 

However, the short life span of stem cells outside the lab and the vaccination’s severe inflammatory side effects are limitations. Researchers won’t be able to conduct clinical trials until these issues are overcome.

• How to overcome limitations in research

You’ve already started on the road to overcoming limitations in research by acknowledging that they exist. However, you need to ensure readers don’t mistake weaknesses for errors within your research design.

To do this, you’ll need to justify and explain your rationale for the methods, research design, and analysis tools you chose and how you noticed they may have presented limitations.

Your readers need to know that even when limitations presented themselves, you followed best practices and the ethical standards of your field. You didn’t violate any rules and regulations during your research process.

You’ll also want to reinforce the validity of your conclusions and results with multiple sources, methods, and perspectives. This prevents readers from assuming your findings were derived from a single or biased source.

• Learning and improving starts with limitations in research

Dealing with limitations with transparency and integrity helps identify areas for future improvements and developments. It’s a learning process, providing valuable insights into how you can improve methodologies, expand sample sizes, or explore alternate approaches to further support the validity of your findings.

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21 Research Limitations Examples

Chris Drew (PhD)

Dr. Chris Drew is the founder of the Helpful Professor. He holds a PhD in education and has published over 20 articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education. [Image Descriptor: Photo of Chris]

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Research limitations refer to the potential weaknesses inherent in a study. All studies have limitations of some sort, meaning declaring limitations doesn’t necessarily need to be a bad thing, so long as your declaration of limitations is well thought-out and explained.

Rarely is a study perfect. Researchers have to make trade-offs when developing their studies, which are often based upon practical considerations such as time and monetary constraints, weighing the breadth of participants against the depth of insight, and choosing one methodology or another.

In research, studies can have limitations such as limited scope, researcher subjectivity, and lack of available research tools.

Acknowledging the limitations of your study should be seen as a strength. It demonstrates your willingness for transparency, humility, and submission to the scientific method and can bolster the integrity of the study. It can also inform future research direction.

Typically, scholars will explore the limitations of their study in either their methodology section, their conclusion section, or both.

Research Limitations Examples

Qualitative and quantitative research offer different perspectives and methods in exploring phenomena, each with its own strengths and limitations. So, I’ve split the limitations examples sections into qualitative and quantitative below.

Qualitative Research Limitations

Qualitative research seeks to understand phenomena in-depth and in context. It focuses on the ‘why’ and ‘how’ questions.

It’s often used to explore new or complex issues, and it provides rich, detailed insights into participants’ experiences, behaviors, and attitudes. However, these strengths also create certain limitations, as explained below.

1. Subjectivity

Qualitative research often requires the researcher to interpret subjective data. One researcher may examine a text and identify different themes or concepts as more dominant than others.

Close qualitative readings of texts are necessarily subjective – and while this may be a limitation, qualitative researchers argue this is the best way to deeply understand everything in context.

Suggested Solution and Response: To minimize subjectivity bias, you could consider cross-checking your own readings of themes and data against other scholars’ readings and interpretations. This may involve giving the raw data to a supervisor or colleague and asking them to code the data separately, then coming together to compare and contrast results.

2. Researcher Bias

The concept of researcher bias is related to, but slightly different from, subjectivity.

Researcher bias refers to the perspectives and opinions you bring with you when doing your research.

For example, a researcher who is explicitly of a certain philosophical or political persuasion may bring that persuasion to bear when interpreting data.

In many scholarly traditions, we will attempt to minimize researcher bias through the utilization of clear procedures that are set out in advance or through the use of statistical analysis tools.

However, in other traditions, such as in postmodern feminist research , declaration of bias is expected, and acknowledgment of bias is seen as a positive because, in those traditions, it is believed that bias cannot be eliminated from research, so instead, it is a matter of integrity to present it upfront.

Suggested Solution and Response: Acknowledge the potential for researcher bias and, depending on your theoretical framework , accept this, or identify procedures you have taken to seek a closer approximation to objectivity in your coding and analysis.

3. Generalizability

If you’re struggling to find a limitation to discuss in your own qualitative research study, then this one is for you: all qualitative research, of all persuasions and perspectives, cannot be generalized.

This is a core feature that sets qualitative data and quantitative data apart.

The point of qualitative data is to select case studies and similarly small corpora and dig deep through in-depth analysis and thick description of data.

Often, this will also mean that you have a non-randomized sample size.

While this is a positive – you’re going to get some really deep, contextualized, interesting insights – it also means that the findings may not be generalizable to a larger population that may not be representative of the small group of people in your study.

Suggested Solution and Response: Suggest future studies that take a quantitative approach to the question.

4. The Hawthorne Effect

The Hawthorne effect refers to the phenomenon where research participants change their ‘observed behavior’ when they’re aware that they are being observed.

This effect was first identified by Elton Mayo who conducted studies of the effects of various factors ton workers’ productivity. He noticed that no matter what he did – turning up the lights, turning down the lights, etc. – there was an increase in worker outputs compared to prior to the study taking place.

Mayo realized that the mere act of observing the workers made them work harder – his observation was what was changing behavior.

So, if you’re looking for a potential limitation to name for your observational research study , highlight the possible impact of the Hawthorne effect (and how you could reduce your footprint or visibility in order to decrease its likelihood).

Suggested Solution and Response: Highlight ways you have attempted to reduce your footprint while in the field, and guarantee anonymity to your research participants.

5. Replicability

Quantitative research has a great benefit in that the studies are replicable – a researcher can get a similar sample size, duplicate the variables, and re-test a study. But you can’t do that in qualitative research.

Qualitative research relies heavily on context – a specific case study or specific variables that make a certain instance worthy of analysis. As a result, it’s often difficult to re-enter the same setting with the same variables and repeat the study.

Furthermore, the individual researcher’s interpretation is more influential in qualitative research, meaning even if a new researcher enters an environment and makes observations, their observations may be different because subjectivity comes into play much more. This doesn’t make the research bad necessarily (great insights can be made in qualitative research), but it certainly does demonstrate a weakness of qualitative research.

6. Limited Scope

“Limited scope” is perhaps one of the most common limitations listed by researchers – and while this is often a catch-all way of saying, “well, I’m not studying that in this study”, it’s also a valid point.

No study can explore everything related to a topic. At some point, we have to make decisions about what’s included in the study and what is excluded from the study.

So, you could say that a limitation of your study is that it doesn’t look at an extra variable or concept that’s certainly worthy of study but will have to be explored in your next project because this project has a clearly and narrowly defined goal.

Suggested Solution and Response: Be clear about what’s in and out of the study when writing your research question.

7. Time Constraints

This is also a catch-all claim you can make about your research project: that you would have included more people in the study, looked at more variables, and so on. But you’ve got to submit this thing by the end of next semester! You’ve got time constraints.

And time constraints are a recognized reality in all research.

But this means you’ll need to explain how time has limited your decisions. As with “limited scope”, this may mean that you had to study a smaller group of subjects, limit the amount of time you spent in the field, and so forth.

Suggested Solution and Response: Suggest future studies that will build on your current work, possibly as a PhD project.

8. Resource Intensiveness

Qualitative research can be expensive due to the cost of transcription, the involvement of trained researchers, and potential travel for interviews or observations.

So, resource intensiveness is similar to the time constraints concept. If you don’t have the funds, you have to make decisions about which tools to use, which statistical software to employ, and how many research assistants you can dedicate to the study.

Suggested Solution and Response: Suggest future studies that will gain more funding on the back of this ‘ exploratory study ‘.

9. Coding Difficulties

Data analysis in qualitative research often involves coding, which can be subjective and complex, especially when dealing with ambiguous or contradicting data.

After naming this as a limitation in your research, it’s important to explain how you’ve attempted to address this. Some ways to ‘limit the limitation’ include:

• Triangulation: Have 2 other researchers code the data as well and cross-check your results with theirs to identify outliers that may need to be re-examined, debated with the other researchers, or removed altogether.
• Procedure: Use a clear coding procedure to demonstrate reliability in your coding process. I personally use the thematic network analysis method outlined in this academic article by Attride-Stirling (2001).

Suggested Solution and Response: Triangulate your coding findings with colleagues, and follow a thematic network analysis procedure.

10. Risk of Non-Responsiveness

There is always a risk in research that research participants will be unwilling or uncomfortable sharing their genuine thoughts and feelings in the study.

This is particularly true when you’re conducting research on sensitive topics, politicized topics, or topics where the participant is expressing vulnerability .

This is similar to the Hawthorne effect (aka participant bias), where participants change their behaviors in your presence; but it goes a step further, where participants actively hide their true thoughts and feelings from you.

Suggested Solution and Response: One way to manage this is to try to include a wider group of people with the expectation that there will be non-responsiveness from some participants.

11. Risk of Attrition

Attrition refers to the process of losing research participants throughout the study.

This occurs most commonly in longitudinal studies , where a researcher must return to conduct their analysis over spaced periods of time, often over a period of years.

Things happen to people over time – they move overseas, their life experiences change, they get sick, change their minds, and even die. The more time that passes, the greater the risk of attrition.

Suggested Solution and Response: One way to manage this is to try to include a wider group of people with the expectation that there will be attrition over time.

12. Difficulty in Maintaining Confidentiality and Anonymity

Given the detailed nature of qualitative data , ensuring participant anonymity can be challenging.

If you have a sensitive topic in a specific case study, even anonymizing research participants sometimes isn’t enough. People might be able to induce who you’re talking about.

Sometimes, this will mean you have to exclude some interesting data that you collected from your final report. Confidentiality and anonymity come before your findings in research ethics – and this is a necessary limiting factor.

Suggested Solution and Response: Highlight the efforts you have taken to anonymize data, and accept that confidentiality and accountability place extremely important constraints on academic research.

13. Difficulty in Finding Research Participants

A study that looks at a very specific phenomenon or even a specific set of cases within a phenomenon means that the pool of potential research participants can be very low.

Compile on top of this the fact that many people you approach may choose not to participate, and you could end up with a very small corpus of subjects to explore. This may limit your ability to make complete findings, even in a quantitative sense.

You may need to therefore limit your research question and objectives to something more realistic.

Suggested Solution and Response: Highlight that this is going to limit the study’s generalizability significantly.

14. Ethical Limitations

Ethical limitations refer to the things you cannot do based on ethical concerns identified either by yourself or your institution’s ethics review board.

This might include threats to the physical or psychological well-being of your research subjects, the potential of releasing data that could harm a person’s reputation, and so on.

Furthermore, even if your study follows all expected standards of ethics, you still, as an ethical researcher, need to allow a research participant to pull out at any point in time, after which you cannot use their data, which demonstrates an overlap between ethical constraints and participant attrition.

Suggested Solution and Response: Highlight that these ethical limitations are inevitable but important to sustain the integrity of the research.

For more on Qualitative Research, Explore my Qualitative Research Guide

Quantitative Research Limitations

Quantitative research focuses on quantifiable data and statistical, mathematical, or computational techniques. It’s often used to test hypotheses, assess relationships and causality, and generalize findings across larger populations.

Quantitative research is widely respected for its ability to provide reliable, measurable, and generalizable data (if done well!). Its structured methodology has strengths over qualitative research, such as the fact it allows for replication of the study, which underpins the validity of the research.

However, this approach is not without it limitations, explained below.

1. Over-Simplification

Quantitative research is powerful because it allows you to measure and analyze data in a systematic and standardized way. However, one of its limitations is that it can sometimes simplify complex phenomena or situations.

In other words, it might miss the subtleties or nuances of the research subject.

For example, if you’re studying why people choose a particular diet, a quantitative study might identify factors like age, income, or health status. But it might miss other aspects, such as cultural influences or personal beliefs, that can also significantly impact dietary choices.

When writing about this limitation, you can say that your quantitative approach, while providing precise measurements and comparisons, may not capture the full complexity of your subjects of study.

Suggested Solution and Response: Suggest a follow-up case study using the same research participants in order to gain additional context and depth.

2. Lack of Context

Another potential issue with quantitative research is that it often focuses on numbers and statistics at the expense of context or qualitative information.

Let’s say you’re studying the effect of classroom size on student performance. You might find that students in smaller classes generally perform better. However, this doesn’t take into account other variables, like teaching style , student motivation, or family support.

When describing this limitation, you might say, “Although our research provides important insights into the relationship between class size and student performance, it does not incorporate the impact of other potentially influential variables. Future research could benefit from a mixed-methods approach that combines quantitative analysis with qualitative insights.”

3. Applicability to Real-World Settings

Oftentimes, experimental research takes place in controlled environments to limit the influence of outside factors.

This control is great for isolation and understanding the specific phenomenon but can limit the applicability or “external validity” of the research to real-world settings.

For example, if you conduct a lab experiment to see how sleep deprivation impacts cognitive performance, the sterile, controlled lab environment might not reflect real-world conditions where people are dealing with multiple stressors.

Therefore, when explaining the limitations of your quantitative study in your methodology section, you could state:

“While our findings provide valuable information about [topic], the controlled conditions of the experiment may not accurately represent real-world scenarios where extraneous variables will exist. As such, the direct applicability of our results to broader contexts may be limited.”

Suggested Solution and Response: Suggest future studies that will engage in real-world observational research, such as ethnographic research.

4. Limited Flexibility

Once a quantitative study is underway, it can be challenging to make changes to it. This is because, unlike in grounded research, you’re putting in place your study in advance, and you can’t make changes part-way through.

Your study design, data collection methods, and analysis techniques need to be decided upon before you start collecting data.

For example, if you are conducting a survey on the impact of social media on teenage mental health, and halfway through, you realize that you should have included a question about their screen time, it’s generally too late to add it.

When discussing this limitation, you could write something like, “The structured nature of our quantitative approach allows for consistent data collection and analysis but also limits our flexibility to adapt and modify the research process in response to emerging insights and ideas.”

Suggested Solution and Response: Suggest future studies that will use mixed-methods or qualitative research methods to gain additional depth of insight.

5. Risk of Survey Error

Surveys are a common tool in quantitative research, but they carry risks of error.

There can be measurement errors (if a question is misunderstood), coverage errors (if some groups aren’t adequately represented), non-response errors (if certain people don’t respond), and sampling errors (if your sample isn’t representative of the population).

For instance, if you’re surveying college students about their study habits , but only daytime students respond because you conduct the survey during the day, your results will be skewed.

In discussing this limitation, you might say, “Despite our best efforts to develop a comprehensive survey, there remains a risk of survey error, including measurement, coverage, non-response, and sampling errors. These could potentially impact the reliability and generalizability of our findings.”

Suggested Solution and Response: Suggest future studies that will use other survey tools to compare and contrast results.

6. Limited Ability to Probe Answers

With quantitative research, you typically can’t ask follow-up questions or delve deeper into participants’ responses like you could in a qualitative interview.

For instance, imagine you are surveying 500 students about study habits in a questionnaire. A respondent might indicate that they study for two hours each night. You might want to follow up by asking them to elaborate on what those study sessions involve or how effective they feel their habits are.

However, quantitative research generally disallows this in the way a qualitative semi-structured interview could.

When discussing this limitation, you might write, “Given the structured nature of our survey, our ability to probe deeper into individual responses is limited. This means we may not fully understand the context or reasoning behind the responses, potentially limiting the depth of our findings.”

Suggested Solution and Response: Suggest future studies that engage in mixed-method or qualitative methodologies to address the issue from another angle.

7. Reliance on Instruments for Data Collection

In quantitative research, the collection of data heavily relies on instruments like questionnaires, surveys, or machines.

The limitation here is that the data you get is only as good as the instrument you’re using. If the instrument isn’t designed or calibrated well, your data can be flawed.

For instance, if you’re using a questionnaire to study customer satisfaction and the questions are vague, confusing, or biased, the responses may not accurately reflect the customers’ true feelings.

When discussing this limitation, you could say, “Our study depends on the use of questionnaires for data collection. Although we have put significant effort into designing and testing the instrument, it’s possible that inaccuracies or misunderstandings could potentially affect the validity of the data collected.”

Suggested Solution and Response: Suggest future studies that will use different instruments but examine the same variables to triangulate results.

8. Time and Resource Constraints (Specific to Quantitative Research)

Quantitative research can be time-consuming and resource-intensive, especially when dealing with large samples.

It often involves systematic sampling, rigorous design, and sometimes complex statistical analysis.

If resources and time are limited, it can restrict the scale of your research, the techniques you can employ, or the extent of your data analysis.

For example, you may want to conduct a nationwide survey on public opinion about a certain policy. However, due to limited resources, you might only be able to survey people in one city.

When writing about this limitation, you could say, “Given the scope of our research and the resources available, we are limited to conducting our survey within one city, which may not fully represent the nationwide public opinion. Hence, the generalizability of the results may be limited.”

Suggested Solution and Response: Suggest future studies that will have more funding or longer timeframes.

How to Discuss Your Research Limitations

1. in your research proposal and methodology section.

In the research proposal, which will become the methodology section of your dissertation, I would recommend taking the four following steps, in order:

• Be Explicit about your Scope – If you limit the scope of your study in your research question, aims, and objectives, then you can set yourself up well later in the methodology to say that certain questions are “outside the scope of the study.” For example, you may identify the fact that the study doesn’t address a certain variable, but you can follow up by stating that the research question is specifically focused on the variable that you are examining, so this limitation would need to be looked at in future studies.
• Acknowledge the Limitation – Acknowledging the limitations of your study demonstrates reflexivity and humility and can make your research more reliable and valid. It also pre-empts questions the people grading your paper may have, so instead of them down-grading you for your limitations; they will congratulate you on explaining the limitations and how you have addressed them!
• Explain your Decisions – You may have chosen your approach (despite its limitations) for a very specific reason. This might be because your approach remains, on balance, the best one to answer your research question. Or, it might be because of time and monetary constraints that are outside of your control.
• Highlight the Strengths of your Approach – Conclude your limitations section by strongly demonstrating that, despite limitations, you’ve worked hard to minimize the effects of the limitations and that you have chosen your specific approach and methodology because it’s also got some terrific strengths. Name the strengths.

Overall, you’ll want to acknowledge your own limitations but also explain that the limitations don’t detract from the value of your study as it stands.

2. In the Conclusion Section or Chapter

In the conclusion of your study, it is generally expected that you return to a discussion of the study’s limitations. Here, I recommend the following steps:

• Acknowledge issues faced – After completing your study, you will be increasingly aware of issues you may have faced that, if you re-did the study, you may have addressed earlier in order to avoid those issues. Acknowledge these issues as limitations, and frame them as recommendations for subsequent studies.
• Suggest further research – Scholarly research aims to fill gaps in the current literature and knowledge. Having established your expertise through your study, suggest lines of inquiry for future researchers. You could state that your study had certain limitations, and “future studies” can address those limitations.
• Suggest a mixed methods approach – Qualitative and quantitative research each have pros and cons. So, note those ‘cons’ of your approach, then say the next study should approach the topic using the opposite methodology or could approach it using a mixed-methods approach that could achieve the benefits of quantitative studies with the nuanced insights of associated qualitative insights as part of an in-study case-study.

Overall, be clear about both your limitations and how those limitations can inform future studies.

In sum, each type of research method has its own strengths and limitations. Qualitative research excels in exploring depth, context, and complexity, while quantitative research excels in examining breadth, generalizability, and quantifiable measures. Despite their individual limitations, each method contributes unique and valuable insights, and researchers often use them together to provide a more comprehensive understanding of the phenomenon being studied.

Attride-Stirling, J. (2001). Thematic networks: an analytic tool for qualitative research. Qualitative research , 1 (3), 385-405. ( Source )

Atkinson, P., Delamont, S., Cernat, A., Sakshaug, J., & Williams, R. A. (2021).  SAGE research methods foundations . London: Sage Publications.

Clark, T., Foster, L., Bryman, A., & Sloan, L. (2021).  Bryman’s social research methods . Oxford: Oxford University Press.

Köhler, T., Smith, A., & Bhakoo, V. (2022). Templates in qualitative research methods: Origins, limitations, and new directions.  Organizational Research Methods ,  25 (2), 183-210. ( Source )

Lenger, A. (2019). The rejection of qualitative research methods in economics.  Journal of Economic Issues ,  53 (4), 946-965. ( Source )

Taherdoost, H. (2022). What are different research approaches? Comprehensive review of qualitative, quantitative, and mixed method research, their applications, types, and limitations.  Journal of Management Science & Engineering Research ,  5 (1), 53-63. ( Source )

Walliman, N. (2021).  Research methods: The basics . New York: Routledge.

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• The Scientist University

How to Present a Research Study’s Limitations

All studies have imperfections, but how to present them without diminishing the value of the work can be tricky..

Nathan Ni holds a PhD from Queens University. He is a science editor for The Scientist’s Creative Services Team who strives to better understand and communicate the relationships between health and disease.

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Scientists work with many different limitations. First and foremost, they navigate informational limitations, work around knowledge gaps when designing studies, formulating hypotheses, and analyzing data. They also handle technical limitations, making the most of what their hands, equipment, and instruments can achieve. Finally, researchers must also manage logistical limitations. Scientists will often experience sample scarcity, financial issues, or simply be unable to access the technology or materials that they want.

All scientific studies have limitations, and no study is perfect. Researchers should not run from this reality, but engage it directly. It is better to directly address the specific limitations of the work in question, and doing so is actually a way to demonstrate an author’s proficiency and aptitude.

Do: Be Transparent

From a practical perspective, being transparent is the main key to directly addressing the specific limitations of a study. Was there an experiment that the researchers wanted to perform but could not, or a sample that existed that the scientists could not obtain? Was there a piece of knowledge that would explain a question raised by the data presented within the current study? If the answer is yes, the authors should mention this and elaborate upon it within the discussion section.

Asking and addressing these questions demonstrates that the authors have knowledge, understanding, and expertise of the subject area beyond what the study directly investigated. It further demonstrates a solid grasp of the existing literature—which means a solid grasp of what others are doing, what techniques they are using, and what limitations impede their own studies. This information helps the authors contextualize where their study fits within what others have discovered, thereby mitigating the perceived effect of a given limitation on the study’s legitimacy. In essence, this strategy turns limitations, often considered weaknesses, into strengths.

For example, in their 2021 Cell Reports study on macrophage polarization mechanisms, dermatologist Alexander Marneros and colleagues wrote the following. 1

A limitation of studying macrophage polarization in vitro is that this approach only partially captures the tissue microenvironment context in which many different factors affect macrophage polarization. However, it is likely that the identified signaling mechanisms that promote polarization in vitro are also critical for polarization mechanisms that occur in vivo. This is supported by our observation that trametinib and panobinostat inhibited M2-type macrophage polarization not only in vitro but also in skin wounds and laser-induced CNV lesions.

This is a very effective structure. In the first sentence ( yellow ), the authors outlined the limitation. In the next sentence ( green ), they offered a rationalization that mitigates the effect of the limitation. Finally, they provided the evidence ( blue ) for this rationalization, using not just information from the literature, but also data that they obtained in their study specifically for this purpose. 

Don't: Be Defensive

It can feel natural to avoid talking about a study’s limitations. Scientists may believe that mentioning the drawbacks still present in their study will jeopardize their chances of publication. As such, researchers will sometimes skirt around the issue. They will present “boilerplate faults”—generalized concerns about sample size/diversity and time limitations that all researchers face—rather than honestly discussing their own study. Alternatively, they will describe their limitations in a defensive manner, positioning their problems as something that “could not be helped”—as something beyond what science can currently achieve.

However, their audience can see through this, because they are largely peers who understand and have experienced how modern research works. They can tell the difference between global challenges faced by every scientific study and limitations that are specific to a single study. Avoiding these specific limitations can therefore betray a lack of confidence that the study is good enough to withstand problems stemming from legitimate limitations. As such, researchers should actively engage with the greater scientific implications of the limitations that they face. Indeed, doing this is actually a way to demonstrate an author’s proficiency and aptitude.

In an example, neurogeneticist Nancy Bonini and colleagues, in their publication in Nature , discussed a question raised by their data that they have elected not to directly investigate in this study, writing “ Among the intriguing questions raised by these data is how senescent glia promote LDs in other glia. ” To show both the legitimacy of the question and how seriously they have considered it, the authors provided a comprehensive summary of the literature in the following seven sentences, offering two hypotheses backed by a combined eight different sources. 2 Rather than shying away from a limitation, they attacked it as something to be curious about and to discuss. This is not just a very effective way of demonstrating their expertise, but it frames the limitation as something that, when overcome, will build upon the present study rather than something that negatively affects the legitimacy of their current findings.

Striking the Right Balance

Scientists have to navigate the fine line between acknowledging the limitations of their study while also not diminishing the effect and value of their own work. To be aware of legitimate limitations and properly assess and dissect them shows a profound understanding of a field, where the study fits within that field, and what the rest of the scientific community are doing and what challenges they face.

All studies are parts of a greater whole. Pretending otherwise is a disservice to the scientific community.

Looking for more information on scientific writing? Check out  The Scientist’ s  TS SciComm  section. Looking for some help putting together a manuscript, a figure, a poster, or anything else?  The Scientist ’s  Scientific Services  may have the professional help that you need.

• He L, et al. Global characterization of macrophage polarization mechanisms and identification of M2-type polarization inhibitors . Cell Rep . 2021;37(5):109955.
• Byrns CN, et al. Senescent glia link mitochondrial dysfunction and lipid accumulation . Nature . 2024.

What are the limitations in research and how to write them?

Learn about the potential limitations in research and how to appropriately address them in order to deliver honest and ethical research.

It is fairly uncommon for researchers to stumble into the term research limitations when working on their research paper. Limitations in research can arise owing to constraints on design, methods, materials, and so on, and these aspects, unfortunately, may have an influence on your subject’s findings.

In this Mind The Graph’s article, we’ll discuss some recommendations for writing limitations in research , provide examples of various common types of limitations, and suggest how to properly present this information.

What are the limitations in research?

The limitations in research are the constraints in design, methods or even researchers’ limitations that affect and influence the interpretation of your research’s ultimate findings. These are limitations on the generalization and usability of findings that emerge from the design of the research and/or the method employed to ensure validity both internally and externally. 

Researchers are usually cautious to acknowledge the limitations of their research in their publications for fear of undermining the research’s scientific validity. No research is faultless or covers every possible angle. As a result, addressing the constraints of your research exhibits honesty and integrity .

Why should include limitations of research in my paper?

Though limitations tackle potential flaws in research, commenting on them at the conclusion of your paper, by demonstrating that you are aware of these limitations and explaining how they impact the conclusions that may be taken from the research, improves your research by disclosing any issues before other researchers or reviewers do . 

Additionally, emphasizing research constraints implies that you have thoroughly investigated the ramifications of research shortcomings and have a thorough understanding of your research problem. 

Limits exist in any research; being honest about them and explaining them would impress researchers and reviewers more than disregarding them. 

Remember that acknowledging a research’s shortcomings offers a chance to provide ideas for future research, but be careful to describe how your study may help to concentrate on these outstanding problems .

Possible limitations examples

Here are some limitations connected to methodology and the research procedure that you may need to explain and discuss in connection to your findings.

Methodological limitations

Sample size.

The number of units of analysis used in your study is determined by the sort of research issue being investigated. It is important to note that if your sample is too small, finding significant connections in the data will be challenging, as statistical tests typically require a larger sample size to ensure a fair representation and this can be limiting. 

Lack of available or reliable data

A lack of data or trustworthy data will almost certainly necessitate limiting the scope of your research or the size of your sample, or it can be a substantial impediment to identifying a pattern and a relevant connection.

Lack of prior research on the subject

Citing previous research papers forms the basis of your literature review and aids in comprehending the research subject you are researching. Yet there may be little if any, past research on your issue.

The measure used to collect data

After finishing your analysis of the findings, you realize that the method you used to collect data limited your capacity to undertake a comprehensive evaluation of the findings. Recognize the flaw by mentioning that future researchers should change the specific approach for data collection.

Issues with research samples and selection

Sampling inaccuracies arise when a probability sampling method is employed to choose a sample, but that sample does not accurately represent the overall population or the relevant group. As a result, your study suffers from “sampling bias” or “selection bias.”

Limitations of the research

When your research requires polling certain persons or a specific group, you may have encountered the issue of limited access to these interviewees. Because of the limited access, you may need to reorganize or rearrange your research. In this scenario, explain why access is restricted and ensure that your findings are still trustworthy and valid despite the constraint.

Time constraints

Practical difficulties may limit the amount of time available to explore a research issue and monitor changes as they occur. If time restrictions have any detrimental influence on your research, recognize this impact by expressing the necessity for a future investigation.

Due to their cultural origins or opinions on observed events, researchers may carry biased opinions, which can influence the credibility of a research. Furthermore, researchers may exhibit biases toward data and conclusions that only support their hypotheses or arguments.

The structure of the limitations section 

The limitations of your research are usually stated at the beginning of the discussion section of your paper so that the reader is aware of and comprehends the limitations prior to actually reading the rest of your findings, or they are stated at the end of the discussion section as an acknowledgment of the need for further research.

The ideal way is to divide your limitations section into three steps: 

1. Identify the research constraints; 

2. Describe in great detail how they affect your research; 

3. Mention the opportunity for future investigations and give possibilities. 

By following this method while addressing the constraints of your research, you will be able to effectively highlight your research’s shortcomings without jeopardizing the quality and integrity of your research.

Present your research or paper in an innovative way

If you want your readers to be engaged and participate in your research, try Mind The Graph tool to add visual assets to your content. Infographics may improve comprehension and are easy to read, just as the Mind The Graph tool is simple to use and offers a variety of templates from which you can select the one that best suits your information.

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How to Present the Limitations of a Study in Research?

The limitations of the study convey to the reader how and under which conditions your study results will be evaluated. Scientific research involves investigating research topics, both known and unknown, which inherently includes an element of risk. The risk could arise due to human errors, barriers to data gathering, limited availability of resources, and researcher bias. Researchers are encouraged to discuss the limitations of their research to enhance the process of research, as well as to allow readers to gain an understanding of the study’s framework and value.

Limitations of the research are the constraints placed on the ability to generalize from the results and to further describe applications to practice. It is related to the utility value of the findings based on how you initially chose to design the study, the method used to establish internal and external validity, or the result of unanticipated challenges that emerged during the study. Knowing about these limitations and their impact can explain how the limitations of your study can affect the conclusions and thoughts drawn from your research. 1

Table of Contents

What are the limitations of a study

Researchers are probably cautious to acknowledge what the limitations of the research can be for fear of undermining the validity of the research findings. No research can be faultless or cover all possible conditions. These limitations of your research appear probably due to constraints on methodology or research design and influence the interpretation of your research’s ultimate findings. 2 These are limitations on the generalization and usability of findings that emerge from the design of the research and/or the method employed to ensure validity internally and externally. But such limitations of the study can impact the whole study or research paper. However, most researchers prefer not to discuss the different types of limitations in research for fear of decreasing the value of their paper amongst the reviewers or readers.

Importance of limitations of a study

Writing the limitations of the research papers is often assumed to require lots of effort. However, identifying the limitations of the study can help structure the research better. Therefore, do not underestimate the importance of research study limitations. 3

• Opportunity to make suggestions for further research. Suggestions for future research and avenues for further exploration can be developed based on the limitations of the study.
• Opportunity to demonstrate critical thinking. A key objective of the research process is to discover new knowledge while questioning existing assumptions and exploring what is new in the particular field. Describing the limitation of the research shows that you have critically thought about the research problem, reviewed relevant literature, and correctly assessed the methods chosen for studying the problem.
• Demonstrate Subjective learning process. Writing limitations of the research helps to critically evaluate the impact of the said limitations, assess the strength of the research, and consider alternative explanations or interpretations. Subjective evaluation contributes to a more complex and comprehensive knowledge of the issue under study.

Why should I include limitations of research in my paper

All studies have limitations to some extent. Including limitations of the study in your paper demonstrates the researchers’ comprehensive and holistic understanding of the research process and topic. The major advantages are the following:

• Understand the study conditions and challenges encountered . It establishes a complete and potentially logical depiction of the research. The boundaries of the study can be established, and realistic expectations for the findings can be set. They can also help to clarify what the study is not intended to address.
• Improve the quality and validity of the research findings. Mentioning limitations of the research creates opportunities for the original author and other researchers to undertake future studies to improve the research outcomes.
• Transparency and accountability. Including limitations of the research helps maintain mutual integrity and promote further progress in similar studies.
• Identify potential bias sources.  Identifying the limitations of the study can help researchers identify potential sources of bias in their research design, data collection, or analysis. This can help to improve the validity and reliability of the findings.

Where do I need to add the limitations of the study in my paper

The limitations of your research can be stated at the beginning of the discussion section, which allows the reader to comprehend the limitations of the study prior to reading the rest of your findings or at the end of the discussion section as an acknowledgment of the need for further research.

Types of limitations in research

There are different types of limitations in research that researchers may encounter. These are listed below:

• Research Design Limitations : Restrictions on your research or available procedures may affect the research outputs. If the research goals and objectives are too broad, explain how they should be narrowed down to enhance the focus of your study. If there was a selection bias in your sample, explain how this may affect the generalizability of your findings. This can help readers understand the limitations of the study in terms of their impact on the overall validity of your research.
• Impact Limitations : Your study might be limited by a strong regional-, national-, or species-based impact or population- or experimental-specific impact. These inherent limitations on impact affect the extendibility and generalizability of the findings.
• Data or statistical limitations : Data or statistical limitations in research are extremely common in experimental (such as medicine, physics, and chemistry) or field-based (such as ecology and qualitative clinical research) studies. Sometimes, it is either extremely difficult to acquire sufficient data or gain access to the data. These limitations of the research might also be the result of your study’s design and might result in an incomplete conclusion to your research.

Limitations of study examples

All possible limitations of the study cannot be included in the discussion section of the research paper or dissertation. It will vary greatly depending on the type and nature of the study. These include types of research limitations that are related to methodology and the research process and that of the researcher as well that you need to describe and discuss how they possibly impacted your results.

Common methodological limitations of the study

Limitations of research due to methodological problems are addressed by identifying the potential problem and suggesting ways in which this should have been addressed. Some potential methodological limitations of the study are as follows. 1

• Sample size: The sample size 4 is dictated by the type of research problem investigated. If the sample size is too small, finding a significant relationship from the data will be difficult, as statistical tests require a large sample size to ensure a representative population distribution and generalize the study findings.
• Lack of available/reliable data: A lack of available/reliable data will limit the scope of your analysis and the size of your sample or present obstacles in finding a trend or meaningful relationship. So, when writing about the limitations of the study, give convincing reasons why you feel data is absent or untrustworthy and highlight the necessity for a future study focused on developing a new data-gathering strategy.
• Lack of prior research studies: Citing prior research studies is required to help understand the research problem being investigated. If there is little or no prior research, an exploratory rather than an explanatory research design will be required. Also, discovering the limitations of the study presents an opportunity to identify gaps in the literature and describe the need for additional study.
• Measure used to collect the data: Sometimes, the data gathered will be insufficient to conduct a thorough analysis of the results. A limitation of the study example, for instance, is identifying in retrospect that a specific question could have helped address a particular issue that emerged during data analysis. You can acknowledge the limitation of the research by stating the need to revise the specific method for gathering data in the future.
• Self-reported data: Self-reported data cannot be independently verified and can contain several potential bias sources, such as selective memory, attribution, and exaggeration. These biases become apparent if they are incongruent with data from other sources.

General limitations of researchers

Limitations related to the researcher can also influence the study outcomes. These should be addressed, and related remedies should be proposed.

• Limited access to data : If your study requires access to people, organizations, data, or documents whose access is denied or limited, the reasons need to be described. An additional explanation stating why this limitation of research did not prevent you from following through on your study is also needed.
• Time constraints : Researchers might also face challenges in meeting research deadlines due to a lack of timely participant availability or funds, among others. The impacts of time constraints must be acknowledged by mentioning the need for a future study addressing this research problem.
• Conflicts due to biased views and personal issues : Differences in culture or personal views can contribute to researcher bias, as they focus only on the results and data that support their main arguments. To avoid this, pay attention to the problem statement and data gathering.

Steps for structuring the limitations section

Limitations are an inherent part of any research study. Issues may vary, ranging from sampling and literature review to methodology and bias. However, there is a structure for identifying these elements, discussing them, and offering insight or alternatives on how the limitations of the study can be mitigated. This enhances the process of the research and helps readers gain a comprehensive understanding of a study’s conditions.

• Identify the research constraints : Identify those limitations having the greatest impact on the quality of the research findings and your ability to effectively answer your research questions and/or hypotheses. These include sample size, selection bias, measurement error, or other issues affecting the validity and reliability of your research.
• Describe their impact on your research : Reflect on the nature of the identified limitations and justify the choices made during the research to identify the impact of the study’s limitations on the research outcomes. Explanations can be offered if needed, but without being defensive or exaggerating them. Provide context for the limitations of your research to understand them in a broader context. Any specific limitations due to real-world considerations need to be pointed out critically rather than justifying them as done by some other author group or groups.
• Mention the opportunity for future investigations : Suggest ways to overcome the limitations of the present study through future research. This can help readers understand how the research fits into the broader context and offer a roadmap for future studies.

Frequently Asked Questions

• Should I mention all the limitations of my study in the research report?

Restrict limitations to what is pertinent to the research question under investigation. The specific limitations you include will depend on the nature of the study, the research question investigated, and the data collected.

• Can the limitations of a study affect its credibility?

Stating the limitations of the research is considered favorable by editors and peer reviewers. Connecting your study’s limitations with future possible research can help increase the focus of unanswered questions in this area. In addition, admitting limitations openly and validating that they do not affect the main findings of the study increases the credibility of your study. However, if you determine that your study is seriously flawed, explain ways to successfully overcome such flaws in a future study. For example, if your study fails to acquire critical data, consider reframing the research question as an exploratory study to lay the groundwork for more complete research in the future.

• How can I mitigate the limitations of my study?

Strategies to minimize limitations of the research should focus on convincing reviewers and readers that the limitations do not affect the conclusions of the study by showing that the methods are appropriate and that the logic is sound. Here are some steps to follow to achieve this:

• Use data that are valid.
• Use methods that are appropriate and sound logic to draw inferences.
• Use adequate statistical methods for drawing inferences from the data that studies with similar limitations have been published before.

Admit limitations openly and, at the same time, show how they do not affect the main conclusions of the study.

• Can the limitations of a study impact its publication chances?

Limitations in your research can arise owing to restrictions in methodology or research design. Although this could impact your chances of publishing your research paper, it is critical to explain your study’s limitations to your intended audience. For example, it can explain how your study constraints may impact the results and views generated from your investigation. It also shows that you have researched the flaws of your study and have a thorough understanding of the subject.

• How can limitations in research be used for future studies?

The limitations of a study give you an opportunity to offer suggestions for further research. Your study’s limitations, including problems experienced during the study and the additional study perspectives developed, are a great opportunity to take on a new challenge and help advance knowledge in a particular field.

References:

• Brutus, S., Aguinis, H., & Wassmer, U. (2013). Self-reported limitations and future directions in scholarly reports: Analysis and recommendations.  Journal of Management ,  39 (1), 48-75.
• Ioannidis, J. P. (2007). Limitations are not properly acknowledged in the scientific literature.  Journal of Clinical Epidemiology ,  60 (4), 324-329.
• Price, J. H., & Murnan, J. (2004). Research limitations and the necessity of reporting them.  American Journal of Health Education ,  35 (2), 66.
• Boddy, C. R. (2016). Sample size for qualitative research.  Qualitative Market Research: An International Journal ,  19 (4), 426-432.

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Writing Limitations of Research Study — 4 Reasons Why It Is Important!

It is not unusual for researchers to come across the term limitations of research during their academic paper writing. More often this is interpreted as something terrible. However, when it comes to research study, limitations can help structure the research study better. Therefore, do not underestimate significance of limitations of research study.

Allow us to take you through the context of how to evaluate the limits of your research and conclude an impactful relevance to your results.

Table of Contents

What Are the Limitations of a Research Study?

Every research has its limit and these limitations arise due to restrictions in methodology or research design.  This could impact your entire research or the research paper you wish to publish. Unfortunately, most researchers choose not to discuss their limitations of research fearing it will affect the value of their article in the eyes of readers.

However, it is very important to discuss your study limitations and show it to your target audience (other researchers, journal editors, peer reviewers etc.). It is very important that you provide an explanation of how your research limitations may affect the conclusions and opinions drawn from your research. Moreover, when as an author you state the limitations of research, it shows that you have investigated all the weaknesses of your study and have a deep understanding of the subject. Being honest could impress your readers and mark your study as a sincere effort in research.

Why and Where Should You Include the Research Limitations?

The main goal of your research is to address your research objectives. Conduct experiments, get results and explain those results, and finally justify your research question . It is best to mention the limitations of research in the discussion paragraph of your research article.

At the very beginning of this paragraph, immediately after highlighting the strengths of the research methodology, you should write down your limitations. You can discuss specific points from your research limitations as suggestions for further research in the conclusion of your thesis.

1. Common Limitations of the Researchers

Limitations that are related to the researcher must be mentioned. This will help you gain transparency with your readers. Furthermore, you could provide suggestions on decreasing these limitations in you and your future studies.

2. Limited Access to Information

Your work may involve some institutions and individuals in research, and sometimes you may have problems accessing these institutions. Therefore, you need to redesign and rewrite your work. You must explain your readers the reason for limited access.

3. Limited Time

All researchers are bound by their deadlines when it comes to completing their studies. Sometimes, time constraints can affect your research negatively. However, the best practice is to acknowledge it and mention a requirement for future study to solve the research problem in a better way.

4. Conflict over Biased Views and Personal Issues

Biased views can affect the research. In fact, researchers end up choosing only those results and data that support their main argument, keeping aside the other loose ends of the research.

Types of Limitations of Research

Before beginning your research study, know that there are certain limitations to what you are testing or possible research results. There are different types that researchers may encounter, and they all have unique characteristics, such as:

1. Research Design Limitations

Certain restrictions on your research or available procedures may affect your final results or research outputs. You may have formulated research goals and objectives too broadly. However, this can help you understand how you can narrow down the formulation of research goals and objectives, thereby increasing the focus of your study.

2. Impact Limitations

Even if your research has excellent statistics and a strong design, it can suffer from the influence of the following factors:

• Presence of increasing findings as researched
• Being population specific
• A strong regional focus.

3. Data or statistical limitations

In some cases, it is impossible to collect sufficient data for research or very difficult to get access to the data. This could lead to incomplete conclusion to your study. Moreover, this insufficiency in data could be the outcome of your study design. The unclear, shabby research outline could produce more problems in interpreting your findings.

How to Correctly Structure Your Research Limitations?

There are strict guidelines for narrowing down research questions, wherein you could justify and explain potential weaknesses of your academic paper. You could go through these basic steps to get a well-structured clarity of research limitations:

• Declare that you wish to identify your limitations of research and explain their importance,
• Provide the necessary depth, explain their nature, and justify your study choices.
• Write how you are suggesting that it is possible to overcome them in the future.

In this section, your readers will see that you are aware of the potential weaknesses in your business, understand them and offer effective solutions, and it will positively strengthen your article as you clarify all limitations of research to your target audience.

Know that you cannot be perfect and there is no individual without flaws. You could use the limitations of research as a great opportunity to take on a new challenge and improve the future of research. In a typical academic paper, research limitations may relate to:

1. Formulating your goals and objectives

If you formulate goals and objectives too broadly, your work will have some shortcomings. In this case, specify effective methods or ways to narrow down the formula of goals and aim to increase your level of study focus.

2. Application of your data collection methods in research

If you do not have experience in primary data collection, there is a risk that there will be flaws in the implementation of your methods. It is necessary to accept this, and learn and educate yourself to understand data collection methods.

3. Sample sizes

This depends on the nature of problem you choose. Sample size is of a greater importance in quantitative studies as opposed to qualitative ones. If your sample size is too small, statistical tests cannot identify significant relationships or connections within a given data set.

You could point out that other researchers should base the same study on a larger sample size to get more accurate results.

4. The absence of previous studies in the field you have chosen

Writing a literature review is an important step in any scientific study because it helps researchers determine the scope of current work in the chosen field. It is a major foundation for any researcher who must use them to achieve a set of specific goals or objectives.

However, if you are focused on the most current and evolving research problem or a very narrow research problem, there may be very little prior research on your topic. For example, if you chose to explore the role of Bitcoin as the currency of the future, you may not find tons of scientific papers addressing the research problem as Bitcoins are only a new phenomenon.

It is important that you learn to identify research limitations examples at each step. Whatever field you choose, feel free to add the shortcoming of your work. This is mainly because you do not have many years of experience writing scientific papers or completing complex work. Therefore, the depth and scope of your discussions may be compromised at different levels compared to academics with a lot of expertise. Include specific points from limitations of research. Use them as suggestions for the future.

Have you ever faced a challenge of writing the limitations of research study in your paper? How did you overcome it? What ways did you follow? Were they beneficial? Let us know in the comments below!

Frequently Asked Questions

Setting limitations in our study helps to clarify the outcomes drawn from our research and enhance understanding of the subject. Moreover, it shows that the author has investigated all the weaknesses in the study.

Scope is the range and limitations of a research project which are set to define the boundaries of a project. Limitations are the impacts on the overall study due to the constraints on the research design.

Limitation in research is an impact of a constraint on the research design in the overall study. They are the flaws or weaknesses in the study, which may influence the outcome of the research.

1. Limitations in research can be written as follows: Formulate your goals and objectives 2. Analyze the chosen data collection method and the sample sizes 3. Identify your limitations of research and explain their importance 4. Provide the necessary depth, explain their nature, and justify your study choices 5. Write how you are suggesting that it is possible to overcome them in the future

Excellent article ,,,it has helped me big

This is very helpful information. It has given me an insight on how to go about my study limitations.

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the topic is well covered

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Limitations of the Study – How to Write & Examples

What are the limitations of a study?

The limitations of a study are the elements of methodology or study design that impact the interpretation of your research results. The limitations essentially detail any flaws or shortcomings in your study. Study limitations can exist due to constraints on research design, methodology, materials, etc., and these factors may impact the findings of your study. However, researchers are often reluctant to discuss the limitations of their study in their papers, feeling that bringing up limitations may undermine its research value in the eyes of readers and reviewers.

In spite of the impact it might have (and perhaps because of it) you should clearly acknowledge any limitations in your research paper in order to show readers—whether journal editors, other researchers, or the general public—that you are aware of these limitations and to explain how they affect the conclusions that can be drawn from the research.

In this article, we provide some guidelines for writing about research limitations, show examples of some frequently seen study limitations, and recommend techniques for presenting this information. And after you have finished drafting and have received manuscript editing for your work, you still might want to follow this up with academic editing before submitting your work to your target journal.

Why do I need to include limitations of research in my paper?

Although limitations address the potential weaknesses of a study, writing about them toward the end of your paper actually strengthens your study by identifying any problems before other researchers or reviewers find them.

Furthermore, pointing out study limitations shows that you’ve considered the impact of research weakness thoroughly and have an in-depth understanding of your research topic. Since all studies face limitations, being honest and detailing these limitations will impress researchers and reviewers more than ignoring them.

Where should I put the limitations of the study in my paper?

Some limitations might be evident to researchers before the start of the study, while others might become clear while you are conducting the research. Whether these limitations are anticipated or not, and whether they are due to research design or to methodology, they should be clearly identified and discussed in the discussion section —the final section of your paper. Most journals now require you to include a discussion of potential limitations of your work, and many journals now ask you to place this “limitations section” at the very end of your article. 

Some journals ask you to also discuss the strengths of your work in this section, and some allow you to freely choose where to include that information in your discussion section—make sure to always check the author instructions of your target journal before you finalize a manuscript and submit it for peer review .

Limitations of the Study Examples

There are several reasons why limitations of research might exist. The two main categories of limitations are those that result from the methodology and those that result from issues with the researcher(s).

Common Methodological Limitations of Studies

Limitations of research due to methodological problems can be addressed by clearly and directly identifying the potential problem and suggesting ways in which this could have been addressed—and SHOULD be addressed in future studies. The following are some major potential methodological issues that can impact the conclusions researchers can draw from the research.

Issues with research samples and selection

Sampling errors occur when a probability sampling method is used to select a sample, but that sample does not reflect the general population or appropriate population concerned. This results in limitations of your study known as “sample bias” or “selection bias.”

For example, if you conducted a survey to obtain your research results, your samples (participants) were asked to respond to the survey questions. However, you might have had limited ability to gain access to the appropriate type or geographic scope of participants. In this case, the people who responded to your survey questions may not truly be a random sample.

Insufficient sample size for statistical measurements

When conducting a study, it is important to have a sufficient sample size in order to draw valid conclusions. The larger the sample, the more precise your results will be. If your sample size is too small, it will be difficult to identify significant relationships in the data.

Normally, statistical tests require a larger sample size to ensure that the sample is considered representative of a population and that the statistical result can be generalized to a larger population. It is a good idea to understand how to choose an appropriate sample size before you conduct your research by using scientific calculation tools—in fact, many journals now require such estimation to be included in every manuscript that is sent out for review.

Lack of previous research studies on the topic

Citing and referencing prior research studies constitutes the basis of the literature review for your thesis or study, and these prior studies provide the theoretical foundations for the research question you are investigating. However, depending on the scope of your research topic, prior research studies that are relevant to your thesis might be limited.

When there is very little or no prior research on a specific topic, you may need to develop an entirely new research typology. In this case, discovering a limitation can be considered an important opportunity to identify literature gaps and to present the need for further development in the area of study.

Methods/instruments/techniques used to collect the data

After you complete your analysis of the research findings (in the discussion section), you might realize that the manner in which you have collected the data or the ways in which you have measured variables has limited your ability to conduct a thorough analysis of the results.

For example, you might realize that you should have addressed your survey questions from another viable perspective, or that you were not able to include an important question in the survey. In these cases, you should acknowledge the deficiency or deficiencies by stating a need for future researchers to revise their specific methods for collecting data that includes these missing elements.

Common Limitations of the Researcher(s)

Study limitations that arise from situations relating to the researcher or researchers (whether the direct fault of the individuals or not) should also be addressed and dealt with, and remedies to decrease these limitations—both hypothetically in your study, and practically in future studies—should be proposed.

Limited access to data

If your research involved surveying certain people or organizations, you might have faced the problem of having limited access to these respondents. Due to this limited access, you might need to redesign or restructure your research in a different way. In this case, explain the reasons for limited access and be sure that your finding is still reliable and valid despite this limitation.

Time constraints

Just as students have deadlines to turn in their class papers, academic researchers might also have to meet deadlines for submitting a manuscript to a journal or face other time constraints related to their research (e.g., participants are only available during a certain period; funding runs out; collaborators move to a new institution). The time available to study a research problem and to measure change over time might be constrained by such practical issues. If time constraints negatively impacted your study in any way, acknowledge this impact by mentioning a need for a future study (e.g., a longitudinal study) to answer this research problem.

Conflicts arising from cultural bias and other personal issues

Researchers might hold biased views due to their cultural backgrounds or perspectives of certain phenomena, and this can affect a study’s legitimacy. Also, it is possible that researchers will have biases toward data and results that only support their hypotheses or arguments. In order to avoid these problems, the author(s) of a study should examine whether the way the research problem was stated and the data-gathering process was carried out appropriately.

Steps for Organizing Your Study Limitations Section

When you discuss the limitations of your study, don’t simply list and describe your limitations—explain how these limitations have influenced your research findings. There might be multiple limitations in your study, but you only need to point out and explain those that directly relate to and impact how you address your research questions.

We suggest that you divide your limitations section into three steps: (1) identify the study limitations; (2) explain how they impact your study in detail; and (3) propose a direction for future studies and present alternatives. By following this sequence when discussing your study’s limitations, you will be able to clearly demonstrate your study’s weakness without undermining the quality and integrity of your research.

Step 1. Identify the limitation(s) of the study

• This part should comprise around 10%-20% of your discussion of study limitations.

The first step is to identify the particular limitation(s) that affected your study. There are many possible limitations of research that can affect your study, but you don’t need to write a long review of all possible study limitations. A 200-500 word critique is an appropriate length for a research limitations section. In the beginning of this section, identify what limitations your study has faced and how important these limitations are.

You only need to identify limitations that had the greatest potential impact on: (1) the quality of your findings, and (2) your ability to answer your research question.

Step 2. Explain these study limitations in detail

• This part should comprise around 60-70% of your discussion of limitations.

After identifying your research limitations, it’s time to explain the nature of the limitations and how they potentially impacted your study. For example, when you conduct quantitative research, a lack of probability sampling is an important issue that you should mention. On the other hand, when you conduct qualitative research, the inability to generalize the research findings could be an issue that deserves mention.

Explain the role these limitations played on the results and implications of the research and justify the choice you made in using this “limiting” methodology or other action in your research. Also, make sure that these limitations didn’t undermine the quality of your dissertation .

Step 3. Propose a direction for future studies and present alternatives (optional)

• This part should comprise around 10-20% of your discussion of limitations.

After acknowledging the limitations of the research, you need to discuss some possible ways to overcome these limitations in future studies. One way to do this is to present alternative methodologies and ways to avoid issues with, or “fill in the gaps of” the limitations of this study you have presented.  Discuss both the pros and cons of these alternatives and clearly explain why researchers should choose these approaches.

Make sure you are current on approaches used by prior studies and the impacts they have had on their findings. Cite review articles or scientific bodies that have recommended these approaches and why. This might be evidence in support of the approach you chose, or it might be the reason you consider your choices to be included as limitations. This process can act as a justification for your approach and a defense of your decision to take it while acknowledging the feasibility of other approaches.

P hrases and Tips for Introducing Your Study Limitations in the Discussion Section

The following phrases are frequently used to introduce the limitations of the study:

• “There may be some possible limitations in this study.”
• “The findings of this study have to be seen in light of some limitations.”
•  “The first is the…The second limitation concerns the…”
•  “The empirical results reported herein should be considered in the light of some limitations.”
• “This research, however, is subject to several limitations.”
• “The primary limitation to the generalization of these results is…”
• “Nonetheless, these results must be interpreted with caution and a number of limitations should be borne in mind.”
• “As with the majority of studies, the design of the current study is subject to limitations.”
• “There are two major limitations in this study that could be addressed in future research. First, the study focused on …. Second ….”

For more articles on research writing and the journal submissions and publication process, visit Wordvice’s Academic Resources page.

And be sure to receive professional English editing and proofreading services , including paper editing services , for your journal manuscript before submitting it to journal editors.

Wordvice Resources

Proofreading & Editing Guide

Writing the Results Section for a Research Paper

How to Write a Literature Review

Research Writing Tips: How to Draft a Powerful Discussion Section

How to Captivate Journal Readers with a Strong Introduction

Tips That Will Make Your Abstract a Success!

APA In-Text Citation Guide for Research Writing

Additional Resources

• Diving Deeper into Limitations and Delimitations (PhD student)
• Organizing Your Social Sciences Research Paper: Limitations of the Study (USC Library)
• Research Limitations (Research Methodology)
• How to Present Limitations and Alternatives (UMASS)

Article References

Pearson-Stuttard, J., Kypridemos, C., Collins, B., Mozaffarian, D., Huang, Y., Bandosz, P.,…Micha, R. (2018). Estimating the health and economic effects of the proposed US Food and Drug Administration voluntary sodium reformulation: Microsimulation cost-effectiveness analysis. PLOS. https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002551

Xu, W.L, Pedersen, N.L., Keller, L., Kalpouzos, G., Wang, H.X., Graff, C,. Fratiglioni, L. (2015). HHEX_23 AA Genotype Exacerbates Effect of Diabetes on Dementia and Alzheimer Disease: A Population-Based Longitudinal Study. PLOS. Retrieved from https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1001853

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Limitations in Medical Research: Recognition, Influence, and Warning

Douglas e. ott.

Mercer University, Macon, Georgia, USA.

Background:

As the number of limitations increases in a medical research article, their consequences multiply and the validity of findings decreases. How often do limitations occur in a medical article? What are the implications of limitation interaction? How often are the conclusions hedged in their explanation?

To identify the number, type, and frequency of limitations and words used to describe conclusion(s) in medical research articles.

Search, analysis, and evaluation of open access research articles from 2021 and 2022 from the Journal of the Society of Laparoscopic and Robotic Surgery and 2022 Surgical Endoscopy for type(s) of limitation(s) admitted to by author(s) and the number of times they occurred. Limitations not admitted to were found, obvious, and not claimed. An automated text analysis was performed for hedging words in conclusion statements. A limitation index score is proposed to gauge the validity of statements and conclusions as the number of limitations increases.

A total of 298 articles were reviewed and analyzed, finding 1,764 limitations. Four articles had no limitations. The average was between 3.7% and 6.9% per article. Hedging, weasel words and words of estimative probability description was found in 95.6% of the conclusions.

Conclusions:

Limitations and their number matter. The greater the number of limitations and ramifications of their effects, the more outcomes and conclusions are affected. Wording ambiguity using hedging or weasel words shows that limitations affect the uncertainty of claims. The limitation index scoring method shows the diminished validity of finding(s) and conclusion(s).

INTRODUCTION

As the number of limitations in a medical research article increases, does their influence have a more significant effect than each one considered separately, making the findings and conclusions less reliable and valid? Limitations are known variables that influence data collection and findings and compromise outcomes, conclusions, and inferences. A large body of work recognizes the effect(s) and consequence(s) of limitations. 1 – 77 Other than the ones known to the author(s), unknown and unrecognized limitations influence research credibility. This study and analysis aim to determine how frequently and what limitations are found in peer-reviewed open-access medical articles for laparoscopic/endoscopic surgeons.

This research is about limitations, how often they occur and explained and/or justified. Failure to disclose limitations in medical writing limits proper decision-making and understanding of the material presented. All articles have limitations and constraints. Not acknowledging limitations is a lack of candor, ignorance, or a deliberate omission. To reduce the suspicion of invalid conclusions limitations and their effects must be acknowledged and explained. This allows for a clearer more focused assessment of the article’s subject matter without explaining its findings and conclusions using hedging and words of estimative probability. 78 , 79

An evaluation of open access research/meta-analysis/case series/methodologies/review articles published in the Journal of the Society of Laparoendoscopic and Robotic Surgery ( JSLS ) for 2021 and 2022 (129) and commentary/guidelines/new technology/practice guidelines/review/SAGES Masters Program articles in Surgical Endoscopy ( Surg Endosc ) for 2022 (169) totaling 298 were read and evaluated by automated text analysis for limitations admitted to by the paper’s authors using such words as “limitations,” “limits,” “shortcomings,” “inadequacies,” “flaws,” “weaknesses,” “constraints,” “deficiencies,” “problems,” and “drawbacks” in the search. Limitations not mentioned were found by reading the paper and assigning type and frequency. The number of hedging and weasel words used to describe the conclusion or validate findings was determined by reading the article and adding them up.

For JSLS , there were 129 articles having 63 different types of limitations. Authors claimed 476, and an additional 32 were found within the article, totaling 508 limitations (93.7% admitted to and 6.3% discovered that were not mentioned). This was a 3.9 limitation average per article. No article said it was free of limitations. The ten most frequent limitations and their rate of occurrence are in Table 1 . The total number of limitations, frequency, and visual depictions are seen in Figures 1A and ​ and 1B 1B .

( A ) Visual depiction of the ranked frequency of limitations for JSLS articles reviewed.

The Ten Most Frequent Limitations Found in JSLS and Surg Endosc Articles

There were 169 articles for Surg Endosc , with 78 different named limitations the authors claimed for a total of 1,162. An additional 94 limitations were found in the articles, totaling 1,256, or 7.4 per article. The authors explicitly stated 92.5% of the limitations, and an additional 7.5% of additional limitations were found within the article. Five claimed zero limitations (5/169 = 3%). The ten most frequent limitations and their rate of occurrence are in Table 1 . The total number of limitations and frequency is shown in Figures 1A and ​ and 1B 1B .

Conclusions were described in hedged, weasel words or words of estimative probability 95.6% of the time (285/298).

A research hypothesis aims to test the idea about expected relationships between variables or to explain an occurrence. The assessment of a hypothesis with limitations embedded in the method reaches a conclusion that is inherently flawed. What is compromised by the limitation(s)? The result is an inferential study in the presence of uncertainty. As the number of limitations increases, the validity of information decreases due to the proliferation of uncertain information. Information gathered and conclusions made in the presence of limitations can be functionally unsound. Hypothesis testing of spurious conditions with limitations and then claiming a conclusion is not a reliable method for generating factual evidence. The authors’ reliance on limitation gathered “evidence” data and asserting that this is valid is spurious reasoning. The bridge between theory and evidence is not through limitations that unquestionably accept findings. A range of conclusion possibilities exists being some percent closer to either more correct or incorrect. Relying on leveraging the pursuit of “fact” in the presence of limitations as the safeguard is akin to the fox watching the hen house. Acknowledgment of the uncertainty limitations create in research and discounting the finding’s reliability would give more credibility to the effort. Shortcomings and widespread misuses of research limitation justifications make findings suspect and falsely justified in many instances.

The JSLS instructions to authors say that in the discussion section of the paper the author(s) must “Comment on any methodological weaknesses of the study” ( http://jsls.sls.org/guidelines-for-authors/ ). In their instructions for authors, Surg Endosc says that in the discussion of the paper, “A paragraph discussing study limitations is required” ( https://www.springer.com/journal/464/submission-guidelines ). A comment for a written article about a limitation should express an opinion or reaction. A paragraph discussing limitations, especially, if there is more than one, requires just that: a paragraph and discussion. These requirements were not met or enforced by JSLS 86% (111/129) of the time and 92.3% (156/169) for Surg Endosc . This is an error in peer reviewing, not adhering to established research publication best practices, and the journals needing to adhere to their guidelines. The International Committee of Medical Journal Editors, uniform requirements for manuscripts recommends that authors “State the limitations of your study, and explore the implications of your findings for future research and for clinical practice or policy. Discuss the influence or association of variables, such as sex and/or gender, on your findings, where appropriate, and the limitations of the data.” It also says, “describe new or substantially modified methods, give reasons for using them, and evaluate their limitations” and “Include in the Discussion section the implications of the findings and their limitations, including implications for future research” and “give references to established methods, including statistical methods (see below); provide references and brief descriptions for methods that have been published but are not well known; describe new or substantially modified methods, give reasons for using them, and evaluate their limitations.” 65 “Reporting guidelines (e.g., CONSORT, 1 ARRIVE 2 ) have been proposed to promote the transparency and accuracy of reporting for biomedical studies, and they often include discussion of limitations as a checklist item. Although such guidelines have been endorsed by high-profile biomedical journals, and compliance with them is associated with improved reporting quality, 3 adherence remains suboptimal.” 4 , 5

Limitations start in the methodologic design phase of research. They require troubleshooting evaluations from the start to consider what limitations exist, what is known and unknown, where, and how to overcome them, and how they will affect the reasonableness and assessment of possible conclusions. A named limitation represents a category with numerous components. Each factor has a unique effect on findings and collectively influences conclusion assessment. Even a single limitation can compromise the study’s implementation and adversely influence research parameters, resulting in diminished value of the findings, outcomes, and conclusions. This becomes more problematic as the number of limitations and their components increase. Any limitation influences a research paper. It is unknown how much and to what extent any limitation affects other limitations, but it does create a cascading domino effect of ever-increasing interactions that compromise findings and conclusions. Considering “research” as a system, it has sensitivity and initial conditions (methodology, data collection, analysis, etc.). The slightest alteration of a study due to limitations can profoundly impact all aspects of the study. The presence and influence of limitations introduce a range of unpredictable influences on findings, results, and conclusions.

Researchers and readers need to pay attention to and discount the effects limitations have on the validity of findings. Richard Feynman said in “Cargo cult science” “the first principle is that you must not fool yourself and you are the easiest person to fool.” 73 We strongly believe our own nonsense or wrong-headed reasoning. Buddhist philosophers say we are attached to our ignorance. Researchers are not critical enough about how they fool themselves regarding their findings with known limitations and then pass them on to readers. The competence of findings with known limitations results in suspect conclusions.

Authors should not ask for dismissal, disregard, or indulgence of their limitations. They should be thoughtful and reflective about the implications and uncertainty the limitations create 67 ; their uncertainties, blind spots, and impact on the research’s relevance. A meaningful presentation of study limitations should describe the limitation, explain its effect, provide possible alternative approaches, and describe steps taken to mitigate the limitation. This was largely absent from the articles reviewed.

Authors use synonyms and phrases describing limitations that hide, deflect, downplay, and divert attention from them, i.e., some drawbacks of the study are …, weaknesses of the study are…, shortcomings are…, and disadvantages of the study are…. They then say their finding(s) lack(s) generalizability, meaning the findings only apply to the study participants or that care, sometimes extreme, must be taken in interpreting the results. Which limitation components are they referring to? Are the authors aware of the extent of their limitations, or are they using convenient phrases to highlight the existence of limitations without detailing their defects?

Limitations negatively weigh on both data and conclusions yet no literature exists to provide a quantifiable measure of this effect. The only acknowledgment is that limitations affect research data and conclusions. The adverse effects of limitations are both specific and contextual to each research article and is part of the parameters that affect research. All the limitations are expressed in words, excuses, and a litany of mea culpas asking for forgiveness and without explaining the extent or magnitude of their impact. It is left to the writer and reader to figure out. It is not known what value writers put on their limitations in the 298 articles reviewed from JSLS and Surg Endosc . Listing limitations without comment and effect on the findings and conclusions is a compromising red flag. Therefore, a limitation scoring method was developed and is proposed to assess the level of suspicion generated by the number of limitations.

It is doubtful that a medical research article is so well designed and executed that there are no limitations. This is doubtful since there are unknown unknowns. This study showed that authors need to acknowledge all the limitations when they are known. They acknowledge the ones they know but do not consider other possibilities. There are the known known limitations; the ones the author(s) are aware of and can be measured, some explained, most not. The known unknowns: limitations authors are aware of but cannot explain or quantify. The unknown unknown limitations: the ones authors are not aware of and have unknown influence(s), i.e., the things they do not know they do not know. These are blind spots (not knowing what they do not know or black swan events). And the unknown knowns; the limitations authors may be aware of but have not disclosed, thoroughly reported, understood, or addressed. They are unexpected and not considered. See Table 2 . 74

Limitations of Known and Unknowns as They Apply to Limitations

It is possible that authors did not identify, want to identify, or acknowledge potential limitations or were unaware of what limitations existed. Cumulative complexity is the result of the presence of multiple limitations because of the accumulation and interaction of limitations and their components. Just mentioning a limitation category and not the specific parts that are the limitation(s) is not enough. Authors telling readers of their known research limitations is a caution to discount the findings and conclusions. At what point does the caution for each limitation, its ramifications, and consequences become a warning? When does the piling up of mistakes, bad and missing data, biases, small sample size, lack of generalizability, confounding factors, etc., reach a point when the findings become s uninterpretable and meaningless? “Caution” indicates a level of potential hazard; a warning is more dire and consequential. Authors use the word “caution” not “warning” to describe their conclusions. There is a point when the number of limitations and their cumulative effects surpasses the point where a caution statement is no longer applicable, and a warning statement is required. This is the reason for establishing a limitations risk score.

Limitations put medical research articles at risk. The accumulation of limitations (variables having additional limitation components) are gaps and flaws diluting the probability of validity. There is currently no assessment method for evaluating the effect(s) of limitations on research outcomes other than awareness that there is an effect. Authors make statements warning that their results may not be reliable or generalizable, and need more research and larger numbers. Just because the weight effect of any given limitation is not known, explained, or how it discounts findings does not negate a causation effect on data, its analysis, and conclusions. Limitation variables and the ramifications of their effects have consequences. The relationship is not zero effect and accumulates with each added limitation.

As a result of this research, a limitation index score (LIS) system and assessment tool were developed. This limitation risk assessment tool gives a scores assessment of the relative validity of conclusions in a medical article having limitations. The adoption of the LIS scoring assessment tool for authors, researchers, editors, reviewers, and readers is a step toward understanding the effects of limitations and their causal relationships to findings and conclusions. The objective is cleaner, tighter methodologies, and better data assessment, to achieve more reliable findings. Adjustments to research conclusions in the presence of limitations are necessary. The degree of modification depends on context. The cumulative effect of this burden must be acknowledged by a tangible reduction and questioning of the legitimacy of statements made under these circumstances. The description calculating the LIS score is detailed in Appendix 1 .

A limitation word or phrase is not one limitation; it is a group of limitations under the heading of that word or phrase having many additional possible components just as an individual named influence. For instance, when an admission of selection bias is noted, the authors do not explain if it was an exclusion criterion, self-selection, nonresponsiveness, lost to follow-up, recruitment error, how it affects external validity, lack of randomization, etc., or any of the least 263 types of known biases causing systematic distortions of the truth whether unintentional or wanton. 40 , 76 Which forms of selection bias are they identifying? 63 Limitations have branches that introduce additional limitations influencing the study’s ability to reach a useful conclusion. Authors rarely tell you the effect consequences and extent limitations have on their study, findings, and conclusions.

This is a sample of limitations and a few of their component variables under the rubric of a single word or phrase. See Table 3 .

A Limitation Word or Phrase is a Limitation Having Additional Components That Are Additional Limitations. When an Author Uses the Limitation Composite Word or Phrase, They Leave out Which One of Its Components is Contributory to the Research Limitations. Each Limitation Interacts with Other Limitations, Creating a Cluster of Cross Complexities of Data, Findings, and Conclusions That Are Tainted and Negatively Affect Findings and Conclusions

Limitations rarely occur alone. If you see one there are many you do not see or appreciate. Limitation s components interact with their own and other limitations, leading to complex connections interacting and discounting the reliability of findings. By how much is context dependent: but it is not zero. Limitations are variables influencing outcomes. As the number of limitations increases, the reliability of the conclusions decreases. How many variables (limitations) does it take to nullify the claims of the findings? The weight and influence of each limitation, its aggregate components, and interconnectedness have an unknown magnitude and effect. The result is a disorderly concoction of hearsay explanations. Table 4 is an example of just two single explanation limitations and some of their components illustrating the complex compounding of their effects on each other.

An Example of Interactions between Only Two Limitations and Some of Their Components Causes 16 Interactions

The novelty of this paper on limitations in medical science is not the identification of research article limitations or their number or frequency; it is the recognition of the multiplier effect(s) limitations and the influence they have on diminishing any conclusion(s) the paper makes. It is possible that limitations contribute to the inability of studies to replicate and why so many are one-time occurrences. Therefore, the generalizability statement that should be given to all readers is BEWARE THERE IS A REDUCTION EFFECT ON THE CONCLUSIONS IN THIS ARTICLE BECAUSE OF ITS LIMITATIONS.

Journals accept studies done with too many limitations, creating forking path situations resulting in an enormous number of possible associations of individual data points as multiple comparisons. 79 The result is confusion, a muddled mess caused by interactions of limitations undermining the ability to make valid inferences. Authors know and acknowledge but rarely explain them or their influence. They also use incomplete and biased databases, biased methods, small sample sizes, and not eliminating confounders, etc., but persist in doing research with these circumstances. Why is that? Is it because when limitations are acknowledged, authors feel justified in their conclusions? It wasn’t my poor research design; it was the limitation(s). How do peer reviewers score and analyze these papers without a method to discount the findings and conclusions in the presence of limitations? What are the calculus editors use to justify papers with multiple limitations, reaching compromised or spurious conclusions? How much caution or warning should a journal say must be taken in interpreting article results? How much? Which results? When? Under what circumstance(s)?

Since a critical component of research is its limitations, the quality and rigor of research are largely defined by, 75 these constraints making it imperative that limitations be exposed and explained. All studies have limitations admitted to or not, and these limitations influence outcomes and conclusions. Unfortunately, they are given insufficient attention, accompanied by feeble excuses, but they all matter. The degrees of freedom of each limitation influence every other limitation, magnifying their ramifications and confusion. Limitations of a scientific article must put the findings in context so the reader can judge the validity and strength of the conclusions. While authors acknowledge the limitations of their study, they influence its legitimacy.

Not only are limitations not properly acknowledged in the scientific literature, 8 but their implications, magnitude, and how they affect a conclusion are not explained or appreciated. Authors work at claiming their work and methods “overcome,” “avoid,” or “circumvent” limitations. Limitations are explained away as “Failure to prove a difference does not prove lack of a difference.” 60 Sample size, bias, confounders, bad data, etc. are not what they seem and do not sully the results. The implication is “trust me.” But that’s not science. Limitations create cognitive distortions and framing (misperception of reality) for the authors and readers. Data in studies with limitations is data having limitations. It was real but tainted.

Limitations are not a trivial aspect of research. It is a tangible something, positive or negative, put into a data set to be analyzed and used to reach a conclusion. How did these extra somethings, known unknowns, not knowns, and unknown knowns, affect the validity of the data set and conclusions? Research presented with the vagaries of explicit limitations is intensified by additional limitations and their component effects on top of the first limitation s , quickly diluting any conclusion making its dependability questionable.

This study’s analysis of limitations in medical articles averaged 3.9% per article for JSLS and 7.4% for Surg Endosc . Authors admit to some and are aware of limitations, but not all of them and discount or leave out others. Limitations were often presented with misleading and hedging language. Authors do not give weight or suggest the percent discount limitations have on the reliance of conclusion(s). Since limitations influence findings, reliability, generalizability, and validity without knowing the magnitude of each and their context, the best that can be said about the conclusions is that they are specific to the study described, context-driven, and suspect.

Limitations mean something is missing, added, incorrect, unseen, unaware of, fabricated, or unknown; circumstances that confuse, confound, and compromise findings and information to the extent that a notice is necessary. All medical articles should have this statement, “Any conclusion drawn from this medical study should be interpreted considering its limitations. Readers should exercise caution, use critical judgement, and consult other sources before accepting these findings. Findings may not be generalizable regardless of sample size, composition, representative data points, and subject groups. Methodologic, analytic, and data collection may have introduced biases or limitations that can affect the accuracy of the results. Controlling for confounding variables, known and unknown, may have influenced the data and/or observations. The accuracy and completeness of the data used to draw a conclusion may not be reliable. The study was specific to time, place, persons, and prevailing circumstances. The weight of each of these factors is unknown to us. Their effect may be limited or compounded and diminish the validity of the proposed conclusions.”

This study and findings are limited and constrained by the limitations of the articles reviewed. They have known and unknown limitations not accounted for, missing data, small sample size, incongruous populations, internal and external validity concerns, confounders, and more. See Tables 2 and ​ and 3 . 3 . Some of these are correctible by the author’s awareness of the consequences of limitations, making plans to address them in the methodology phase of hypothesis assessment and performance of the research to diminish their effects.

Limitations in research articles are expected, but they can be reduced in their effect so that conclusions are closer to being valid. Limitations introduce elements of ignorance and suspicion. They need to be explained so their influence on the believability of the study and its conclusions is closer to meeting construct, content, face, and criterion validity. As the number of limitations increases, common sense, skepticism, study component acceptability, and understanding the ramifications of each limitation are necessary to accept, discount, or reject the author’s findings. As the number of hedging and weasel words used to explain conclusion(s) increases, believability decreases, and raises suspicion regarding claims. Establishing a systematic limitation scoring index limitations for authors, editors, reviewers, and readers and recognizing their cumulative effects will result in a clearer understanding of research content and legitimacy.

How to calculate the Limitation Index Score (LIS). See Tables 5 – 5 . Each limitation admitted to by authors in the article equals (=) one (1) point. Limitations may be generally stated by the author as a broad category, but can have multiple components, such as a retrospective study with these limitation components: 1. data or recall not accurate, 2. data missing, 3. selection bias not controlled, 4. confounders not controlled, 5. no randomization, 6. no blinding, 7. difficult to establish cause and effect, and 8. cannot draw a conclusion of causation. For each component, no matter how many are not explained and corrected, add an additional one (1) point to the score. See Table 2 .

The Limitation Scoring Index is a Numeric Limitation Risk Assessment Score to Rank Risk Categories and Discounting Probability of Validity and Conclusions. The More Limitations in a Study, the Greater the Risk of Unreliable Findings and Conclusions

Limitations May Be Generally Stated by the Author but Have Multiple Components, Such as a Retrospective Study Having Disadvantage Components of 1. Data or Recall Not Accurate, 2. Data Missing, 3. Selection Bias Not Controlled, 4. Confounders Not Controlled, 5. No Randomization, 6. No Blinding, 7 Difficult to Establish Cause and Effect, 8. Results Are Hypothesis Generating, and 9. Cannot Draw a Conclusion of Causation. For Each Component, Not Explained and Corrected, Add an Additional One (1) Point Is Added to the Score. Extra Blanks Are for Additional Limitations

An Automatic 2 Points is Added for Meta-Analysis Studies Since They Have All the Retrospective Detrimental Components. 44 Data from Insurance, State, National, Medicare, and Medicaid, Because of Incorrect Coding, Over Reporting, and Under-Reporting, Etc. Each Component of the Limitation Adds One Additional Point. For Surveys and Questionnaires Add One Additional Point for Each Bias. Extra Blanks Are for Additional Limitations

Automatic Five (5) Points for Manufacturer and User Facility Device Experience (MAUDE) Database Articles. The FDA Access Data Site Says Submissions Can Be “Incomplete, Inaccurate, Untimely, Unverified, or Biased” and “the Incidence or Prevalence of an Event Cannot Be Determined from This Reporting System Alone Due to Under-Reporting of Events, Inaccuracies in Reports, Lack of Verification That the Device Caused the Reported Event, and Lack of Information” and “DR Data Alone Cannot Be Used to Establish Rates of Events, Evaluate a Change in Event Rates over Time or Compare Event Rates between Devices. The Number of Reports Cannot Be Interpreted or Used in Isolation to Reach Conclusions” 80

Total Limitation Index Score

Each limitation not admitted to = two (2) points. A meta-analysis study gets an automatic 2 points since they are retrospective and have detrimental components that should be added to the 2 points. Data from insurance, state, national, Medicare, and Medicaid, because of incorrect coding, over-reporting, and underreporting, etc., score 2 points, and each component adds one additional point. Surveys and questionnaires get 2 points, and add one additional point for each bias. See Table 3 .

Manufacturer and User Facility Device Experience (MAUDE) database articles receive an automatic five (5) points. The FDA access data site says, submissions can be “incomplete, inaccurate, untimely, unverified, or biased” and “the incidence or prevalence of an event cannot be determined from this reporting system alone due to underreporting of events, inaccuracies in reports, lack of verification that the device caused the reported event, and lack of information” and “MDR data alone cannot be used to establish rates of events, evaluate a change in event rates over time or compare event rates between devices. The number of reports cannot be interpreted or used in isolation to reach conclusions.” 80 See Table 4 . Add one additional point for each additional limitation noted in the article.

Add one additional point for each additional limitation and one point for each of its components. Extra blanks are for additional

limitations and their component scores.

Funding sources: none.

Disclosure: none.

Conflict of interests: none.

Acknowledgments: Author would like to thank Lynda Davis for her help with data collection.

References:

All references have been archived at https://archive.org/web/

CPS Online Graduate Studies Research Paper (UNH Manchester Library): Limitations of the Study

• Overview of the Research Process for Capstone Projects
• Types of Research Design
• Selecting a Research Problem
• The Title of Your Research Paper
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• 7 Parts of the Research Paper
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• Qualitative Methods
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• Resources to Help You With the Literature Review
• Non-Textual Elements

Limitations of the Study

• Format of Capstone Research Projects at GSC
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• Acknowledgements
• UNH Scholar's Repository

The limitations of the study are those characteristics of design or methodology that impacted or influenced the interpretation of the findings from your research. They are the constraints on generalizability, applications to practice, and/or utility of findings that are the result of the ways in which you initially chose to design the study and/or the method used to establish internal and external validity.

Price, James H. and Judy Murnan. “Research Limitations and the Necessity of Reporting Them.” American Journal of Health Education 35 (2004): 66-67.

Always acknowledge a study's limitations. It is far better that you identify and acknowledge your study’s limitations than to have them pointed out by your professor and be graded down because you appear to have ignored them.

Keep in mind that acknowledgement of a study's limitations is an opportunity to make suggestions for further research. If you do connect your study's limitations to suggestions for further research, be sure to explain the ways in which these unanswered questions may become more focused because of your study.

Acknowledgement of a study's limitations also provides you with an opportunity to demonstrate that you have thought critically about the research problem, understood the relevant literature published about it, and correctly assessed the methods chosen for studying the problem. A key objective of the research process is not only discovering new knowledge but to also confront assumptions and explore what we don't know.

Claiming limitations is a subjective process because you must evaluate the impact of those limitations . Don't just list key weaknesses and the magnitude of a study's limitations. To do so diminishes the validity of your research because it leaves the reader wondering whether, or in what ways, limitation(s) in your study may have impacted the results and conclusions. Limitations require a critical, overall appraisal and interpretation of their impact. You should answer the question: do these problems with errors, methods, validity, etc. eventually matter and, if so, to what extent?

Price, James H. and Judy Murnan. “Research Limitations and the Necessity of Reporting Them.” American Journal of Health Education 35 (2004): 66-67; Structure: How to Structure the Research Limitations Section of Your Dissertation . Dissertations and Theses: An Online Textbook. Laerd.com.

Descriptions of Possible Limitations

All studies have limitations . However, it is important that you restrict your discussion to limitations related to the research problem under investigation. For example, if a meta-analysis of existing literature is not a stated purpose of your research, it should not be discussed as a limitation. Do not apologize for not addressing issues that you did not promise to investigate in the introduction of your paper.

Here are examples of limitations related to methodology and the research process you may need to describe and to discuss how they possibly impacted your results. Descriptions of limitations should be stated in the past tense because they were discovered after you completed your research.

Possible Methodological Limitations

• Sample size -- the number of the units of analysis you use in your study is dictated by the type of research problem you are investigating. Note that, if your sample size is too small, it will be difficult to find significant relationships from the data, as statistical tests normally require a larger sample size to ensure a representative distribution of the population and to be considered representative of groups of people to whom results will be generalized or transferred. Note that sample size is less relevant in qualitative research.
• Lack of available and/or reliable data -- a lack of data or of reliable data will likely require you to limit the scope of your analysis, the size of your sample, or it can be a significant obstacle in finding a trend and a meaningful relationship. You need to not only describe these limitations but to offer reasons why you believe data is missing or is unreliable. However, don’t just throw up your hands in frustration; use this as an opportunity to describe the need for future research.
• Lack of prior research studies on the topic -- citing prior research studies forms the basis of your literature review and helps lay a foundation for understanding the research problem you are investigating. Depending on the currency or scope of your research topic, there may be little, if any, prior research on your topic. Before assuming this to be true, though, consult with a librarian. In cases when a librarian has confirmed that there is no prior research, you may be required to develop an entirely new research typology [for example, using an exploratory rather than an explanatory research design]. Note again that discovering a limitation can serve as an important opportunity to identify new gaps in the literature and to describe the need for further research.
• Measure used to collect the data -- sometimes it is the case that, after completing your interpretation of the findings, you discover that the way in which you gathered data inhibited your ability to conduct a thorough analysis of the results. For example, you regret not including a specific question in a survey that, in retrospect, could have helped address a particular issue that emerged later in the study. Acknowledge the deficiency by stating a need for future researchers to revise the specific method for gathering data.
• Self-reported data -- whether you are relying on pre-existing data or you are conducting a qualitative research study and gathering the data yourself, self-reported data is limited by the fact that it rarely can be independently verified. In other words, you have to take what people say, whether in interviews, focus groups, or on questionnaires, at face value. However, self-reported data can contain several potential sources of bias that you should be alert to and note as limitations. These biases become apparent if they are incongruent with data from other sources. These are: (1) selective memory [remembering or not remembering experiences or events that occurred at some point in the past]; (2) telescoping [recalling events that occurred at one time as if they occurred at another time]; (3) attribution [the act of attributing positive events and outcomes to one's own agency but attributing negative events and outcomes to external forces]; and, (4) exaggeration [the act of representing outcomes or embellishing events as more significant than is actually suggested from other data].

Possible Limitations of the Researcher

• Access -- if your study depends on having access to people, organizations, or documents and, for whatever reason, access is denied or limited in some way, the reasons for this need to be described.
• Longitudinal effects -- unlike your professor, who can literally devote years [even a lifetime] to studying a single topic, the time available to investigate a research problem and to measure change or stability over time is pretty much constrained by the due date of your assignment. Be sure to choose a research problem that does not require an excessive amount of time to complete the literature review, apply the methodology, and gather and interpret the results. If you're unsure whether you can complete your research within the confines of the assignment's due date, talk to your professor.
• Cultural and other type of bias -- we all have biases, whether we are conscience of them or not. Bias is when a person, place, or thing is viewed or shown in a consistently inaccurate way. Bias is usually negative, though one can have a positive bias as well, especially if that bias reflects your reliance on research that only support for your hypothesis. When proof-reading your paper, be especially critical in reviewing how you have stated a problem, selected the data to be studied, what may have been omitted, the manner in which you have ordered events, people, or places, how you have chosen to represent a person, place, or thing, to name a phenomenon, or to use possible words with a positive or negative connotation.

NOTE:   If you detect bias in prior research, it must be acknowledged and you should explain what measures were taken to avoid perpetuating that bias.

• Fluency in a language -- if your research focuses on measuring the perceived value of after-school tutoring among Mexican-American ESL [English as a Second Language] students, for example, and you are not fluent in Spanish, you are limited in being able to read and interpret Spanish language research studies on the topic. This deficiency should be acknowledged.

Aguinis, Hermam and Jeffrey R. Edwards. “Methodological Wishes for the Next Decade and How to Make Wishes Come True.” Journal of Management Studies 51 (January 2014): 143-174; Brutus, Stéphane et al. "Self-Reported Limitations and Future Directions in Scholarly Reports: Analysis and Recommendations." Journal of Management 39 (January 2013): 48-75; Senunyeme, Emmanuel K. Business Research Methods . Powerpoint Presentation. Regent University of Science and Technology; ter Riet, Gerben et al. “All That Glitters Isn't Gold: A Survey on Acknowledgment of Limitations in Biomedical Studies.” PLOS One 8 (November 2013): 1-6.

Structure and Writing Style

Information about the limitations of your study are generally placed either at the beginning of the discussion section of your paper so the reader knows and understands the limitations before reading the rest of your analysis of the findings, or, the limitations are outlined at the conclusion of the discussion section as an acknowledgement of the need for further study. Statements about a study's limitations should not be buried in the body [middle] of the discussion section unless a limitation is specific to something covered in that part of the paper. If this is the case, though, the limitation should be reiterated at the conclusion of the section. If you determine that your study is seriously flawed due to important limitations, such as, an inability to acquire critical data, consider reframing it as an exploratory study intended to lay the groundwork for a more complete research study in the future. Be sure, though, to specifically explain the ways that these flaws can be successfully overcome in a new study. But, do not use this as an excuse for not developing a thorough research paper! Review the tab in this guide for developing a research topic. If serious limitations exist, it generally indicates a likelihood that your research problem is too narrowly defined or that the issue or event under study is too recent and, thus, very little research has been written about it. If serious limitations do emerge, consult with your professor about possible ways to overcome them or how to revise your study. When discussing the limitations of your research, be sure to: Describe each limitation in detailed but concise terms; Explain why each limitation exists; Provide the reasons why each limitation could not be overcome using the method(s) chosen to acquire or gather the data [cite to other studies that had similar problems when possible]; Assess the impact of each limitation in relation to the overall findings and conclusions of your study; and, If appropriate, describe how these limitations could point to the need for further research. Remember that the method you chose may be the source of a significant limitation that has emerged during your interpretation of the results [for example, you didn't interview a group of people that you later wish you had]. If this is the case, don't panic. Acknowledge it, and explain how applying a different or more robust methodology might address the research problem more effectively in a future study. A underlying goal of scholarly research is not only to show what works, but to demonstrate what doesn't work or what needs further clarification. Aguinis, Hermam and Jeffrey R. Edwards. “Methodological Wishes for the Next Decade and How to Make Wishes Come True.” Journal of Management Studies 51 (January 2014): 143-174; Brutus, Stéphane et al. "Self-Reported Limitations and Future Directions in Scholarly Reports: Analysis and Recommendations." Journal of Management 39 (January 2013): 48-75; Ioannidis, John P.A. "Limitations are not Properly Acknowledged in the Scientific Literature." Journal of Clinical Epidemiology 60 (2007): 324-329; Pasek, Josh. Writing the Empirical Social Science Research Paper: A Guide for the Perplexed. January 24, 2012. Academia.edu; Structure: How to Structure the Research Limitations Section of Your Dissertation. Dissertations and Theses: An Online Textbook. Laerd.com; What Is an Academic Paper? Institute for Writing Rhetoric. Dartmouth College; Writing the Experimental Report: Methods, Results, and Discussion. The Writing Lab and The OWL. Purdue University.

Information about the limitations of your study are generally placed either at the beginning of the discussion section of your paper so the reader knows and understands the limitations before reading the rest of your analysis of the findings, or, the limitations are outlined at the conclusion of the discussion section as an acknowledgement of the need for further study. Statements about a study's limitations should not be buried in the body [middle] of the discussion section unless a limitation is specific to something covered in that part of the paper. If this is the case, though, the limitation should be reiterated at the conclusion of the section.

If you determine that your study is seriously flawed due to important limitations , such as, an inability to acquire critical data, consider reframing it as an exploratory study intended to lay the groundwork for a more complete research study in the future. Be sure, though, to specifically explain the ways that these flaws can be successfully overcome in a new study.

But, do not use this as an excuse for not developing a thorough research paper! Review the tab in this guide for developing a research topic . If serious limitations exist, it generally indicates a likelihood that your research problem is too narrowly defined or that the issue or event under study is too recent and, thus, very little research has been written about it. If serious limitations do emerge, consult with your professor about possible ways to overcome them or how to revise your study.

When discussing the limitations of your research, be sure to:

• Describe each limitation in detailed but concise terms;
• Explain why each limitation exists;
• Provide the reasons why each limitation could not be overcome using the method(s) chosen to acquire or gather the data [cite to other studies that had similar problems when possible];
• Assess the impact of each limitation in relation to the overall findings and conclusions of your study; and,
• If appropriate, describe how these limitations could point to the need for further research.

Remember that the method you chose may be the source of a significant limitation that has emerged during your interpretation of the results [for example, you didn't interview a group of people that you later wish you had]. If this is the case, don't panic. Acknowledge it, and explain how applying a different or more robust methodology might address the research problem more effectively in a future study. A underlying goal of scholarly research is not only to show what works, but to demonstrate what doesn't work or what needs further clarification.

Aguinis, Hermam and Jeffrey R. Edwards. “Methodological Wishes for the Next Decade and How to Make Wishes Come True.” Journal of Management Studies 51 (January 2014): 143-174; Brutus, Stéphane et al. "Self-Reported Limitations and Future Directions in Scholarly Reports: Analysis and Recommendations." Journal of Management 39 (January 2013): 48-75; Ioannidis, John P.A. "Limitations are not Properly Acknowledged in the Scientific Literature." Journal of Clinical Epidemiology 60 (2007): 324-329; Pasek, Josh. Writing the Empirical Social Science Research Paper: A Guide for the Perplexed . January 24, 2012. Academia.edu; Structure: How to Structure the Research Limitations Section of Your Dissertation . Dissertations and Theses: An Online Textbook. Laerd.com; What Is an Academic Paper? Institute for Writing Rhetoric. Dartmouth College; Writing the Experimental Report: Methods, Results, and Discussion . The Writing Lab and The OWL. Purdue University.

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Research Limitations & Delimitations

What they are and how they’re different (with examples)

By: Derek Jansen (MBA) | Expert Reviewed By: David Phair (PhD) | September 2022

If you’re new to the world of research, you’ve probably heard the terms “ research limitations ” and “ research delimitations ” being thrown around, often quite loosely. In this post, we’ll unpack what both of these mean, how they’re similar and how they’re different – so that you can write up these sections the right way.

Overview: Limitations vs Delimitations

• Are they the same?
• What are research limitations
• What are research delimitations
• Limitations vs delimitations

First things first…

Let’s start with the most important takeaway point of this post – research limitations and research delimitations are not the same – but they are related to each other (we’ll unpack that a little later). So, if you hear someone using these two words interchangeably, be sure to share this post with them!

Research Limitations

Research limitations are, at the simplest level, the weaknesses of the study , based on factors that are often outside of your control as the researcher. These factors could include things like time , access to funding, equipment , data or participants . For example, if you weren’t able to access a random sample of participants for your study and had to adopt a convenience sampling strategy instead, that would impact the generalizability of your findings and therefore reflect a limitation of your study.

Research limitations can also emerge from the research design itself . For example, if you were undertaking a correlational study, you wouldn’t be able to infer causality (since correlation doesn’t mean certain causation). Similarly, if you utilised online surveys to collect data from your participants, you naturally wouldn’t be able to get the same degree of rich data that you would from in-person interviews .

Simply put, research limitations reflect the shortcomings of a study , based on practical (or theoretical) constraints that the researcher faced. These shortcomings limit what you can conclude from a study, but at the same time, present a foundation for future research . Importantly, all research has limitations , so there’s no need to hide anything here – as long as you discuss how the limitations might affect your findings, it’s all good.

Research Delimitations

Alright, now that we’ve unpacked the limitations, let’s move on to the delimitations .

Research delimitations are similar to limitations in that they also “ limit ” the study, but their focus is entirely different. Specifically, the delimitations of a study refer to the scope of the research aims and research questions . In other words, delimitations reflect the choices you, as the researcher, intentionally make in terms of what you will and won’t try to achieve with your study. In other words, what your research aims and research questions will and won’t include.

As we’ve spoken about many times before, it’s important to have a tight, narrow focus for your research, so that you can dive deeply into your topic, apply your energy to one specific area and develop meaningful insights. If you have an overly broad scope or unfocused topic, your research will often pull in multiple, even opposing directions, and you’ll just land up with a muddy mess of findings .

So, the delimitations section is where you’ll clearly state what your research aims and research questions will focus on – and just as importantly, what they will exclude . For example, you might investigate a widespread phenomenon, but choose to focus your study on a specific age group, ethnicity or gender. Similarly, your study may focus exclusively on one country, city or even organization. As long as the scope is well justified (in other words, it represents a novel, valuable research topic), this is perfectly acceptable – in fact, it’s essential. Remember, focus is your friend.

Need a helping hand?

Conclusion: Limitations vs Delimitations

Ok, so let’s recap.

Research limitations and research delimitations are related in that they both refer to “limits” within a study. But, they are distinctly different. Limitations reflect the shortcomings of your study, based on practical or theoretical constraints that you faced.

Contrasted to that, delimitations reflect the choices that you made in terms of the focus and scope of your research aims and research questions. If you want to learn more about research aims and questions, you can check out this video post , where we unpack those concepts in detail.

Psst... there’s more!

This post was based on one of our popular Research Bootcamps . If you're working on a research project, you'll definitely want to check this out ...

18 Comments

Good clarification of ideas on how a researcher ought to do during Process of choice

Thank you so much for this very simple but explicit explanation on limitation and delimitation. It has so helped me to develop my masters proposal. hope to recieve more from your site as time progresses

Thank you for this explanation – very clear.

Thanks for the explanation, really got it well.

This website is really helpful for my masters proposal

Thank you very much for helping to explain these two terms

I spent almost the whole day trying to figure out the differences

when I came across your notes everything became very clear

thanks for the clearly outlined explanation on the two terms, limitation and delimitation.

Very helpful Many thanks 🙏

Excellent it resolved my conflict .

I would like you to assist me please. If in my Research, I interviewed some participants and I submitted Questionnaires to other participants to answered to the questions, in the same organization, Is this a Qualitative methodology , a Quantitative Methodology or is it a Mixture Methodology I have used in my research? Please help me

How do I cite this article in APA format

Really so great ,finally have understood it’s difference now

Getting more clear regarding Limitations and Delimitation and concepts

I really appreciate your apt and precise explanation of the two concepts namely ; Limitations and Delimitations.

This is a good sources of research information for learners.

thank you for this, very helpful to researchers

Very good explained

Great and clear explanation, after a long confusion period on the two words, i can now explain to someone with ease.

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TRIO McNair Undergraduate Research Guide: Limitations of the Study

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The limitations of the study are those characteristics of design or methodology that impacted or influenced the application or interpretation of the results of your study. They are the constraints on generalizability and utility of findings that are the result of the ways in which you chose to design the study and/or the method used to establish internal and external validity. 

Importance of...

Always acknowledge a study's limitations. It is far better for you to identify and acknowledge your study’s limitations than to have them pointed out by your professor and be graded down because you appear to have ignored them. 

Keep in mind that acknowledgement of a study's limitations is an opportunity to make suggestions for further research . If you do connect your study's limitations to suggestions for further research, be sure to explain the ways in which these unanswered questions may become more focused because of your study. 

Acknowledgement of a study's limitations also provides you with an opportunity to demonstrate to your professor that you have thought critically about the research problem, understood the relevant literature published about it, and correctly assessed the methods chosen for studying the problem. A key objective of the research process is not only discovering new knowledge but also to confront assumptions and explore what we don't know. 

Claiming limitations is a subjective process because you must evaluate the impact of those limitations. Don't just list key weaknesses and the magnitude of a study's limitations. To do so diminishes the validity of your research because it leaves the reader wondering whether, or in what ways, limitation(s) in your study may have impacted the findings and conclusions. Limitations require a critical, overall appraisal and interpretation of their impact. You should answer the question: do these problems with errors, methods, validity, etc. eventually matter and, if so, to what extent? 

Structure: How to Structure the Research Limitations Section of Your Dissertation . Dissertations and Theses: An Online Textbook. Laerd.com.

Descriptions of Possible Limitations

All studies have limitations. However, it is important that you restrict your discussion to limitations related to the research problem under investigation. For example, if a meta-analysis of existing literature is not a stated purpose of your research, it should not be discussed as a limitation. Do not apologize for not addressing issues that you did not promise to investigate in your paper. 

Here are examples of limitations you may need to describe and to discuss how they possibly impacted your findings. Descriptions of limitations should be stated in the past tense. 

Possible Methodological Limitations 

Sample size -- the number of the units of analysis you use in your study is dictated by the type of research problem you are investigating. Note that, if your sample size is too small, it will be difficult to find significant relationships from the data, as statistical tests normally require a larger sample size to ensure a representative distribution of the population and to be considered representative of groups of people to whom results will be generalized or transferred. 

Lack of available and/or reliable data -- a lack of data or of reliable data will likely require you to limit the scope of your analysis, the size of your sample, or it can be a significant obstacle in finding a trend and a meaningful relationship. You need to not only describe these limitations but to offer reasons why you believe data is missing or is unreliable. However, don’t just throw up your hands in frustration; use this as an opportunity to describe the need for future research. 

Lack of prior research studies on the topic -- citing prior research studies forms the basis of your literature review and helps lay a foundation for understanding the research problem you are investigating. Depending on the currency or scope of your research topic, there may be little, if any, prior research on your topic. Before assuming this to be true, consult with a librarian! In cases when a librarian has confirmed that there is a lack of prior research, you may be required to develop an entirely new research typology [for example, using an exploratory rather than an explanatory research design]. Note that this limitation can serve as an important opportunity to describe the need for further research. 

Measure used to collect the data -- sometimes it is the case that, after completing your interpretation of the findings, you discover that the way in which you gathered data inhibited your ability to conduct a thorough analysis of the results. For example, you regret not including a specific question in a survey that, in retrospect, could have helped address a particular issue that emerged later in the study. Acknowledge the deficiency by stating a need in future research to revise the specific method for gathering data. 

Self-reported data -- whether you are relying on pre-existing self-reported data or you are conducting a qualitative research study and gathering the data yourself, self-reported data is limited by the fact that it rarely can be independently verified. In other words, you must take what people say, whether in interviews, focus groups, or on questionnaires, at face value. However, self-reported data contain several potential sources of bias that should be noted as limitations: (1) selective memory (remembering or not remembering experiences or events that occurred at some point in the past); (2) telescoping [recalling events that occurred at one time as if they occurred at another time]; (3) attribution [the act of attributing positive events and outcomes to one's own agency but attributing negative events and outcomes to external forces]; and, (4) exaggeration [the act of representing outcomes or embellishing events as more significant than is actually suggested from other data]. 

Possible Limitations of the Researcher 

Access -- if your study depends on having access to people, organizations, or documents and, for whatever reason, access is denied or otherwise limited, the reasons for this need to be described. 

Longitudinal effects -- unlike your professor, who can devote years [even a lifetime] to studying a single research problem, the time available to investigate a research problem and to measure change or stability within a sample is constrained by the due date of your assignment. Be sure to choose a topic that does not require an excessive amount of time to complete the literature review, apply the methodology, and gather and interpret the results. If you're unsure, talk to your professor. 

Cultural and other types of bias -- we all have biases, whether we are conscience of them or not. Bias is when a person, place, or thing is viewed or shown in a consistently inaccurate way. It is usually negative, though one can have a positive bias as well. When proof-reading your paper, be especially critical in reviewing how you have stated a problem, selected the data to be studied, what may have been omitted, the way you have ordered events, people, or places and how you have chosen to represent a person, place, or thing, to name a phenomenon, or to use possible words with a positive or negative connotation. Note that if you detect bias in prior research, it must be acknowledged, and you should explain what measures were taken to avoid perpetuating bias. 

Fluency in a language -- if your research focuses on measuring the perceived value of after-school tutoring among Mexican American ESL [English as a Second Language] students, for example, and you are not fluent in Spanish, you are limited in being able to read and interpret Spanish language research studies on the topic. This deficiency should be acknowledged. 

Brutus, Stéphane et al. Self-Reported Limitations and Future Directions in Scholarly Reports: Analysis and Recommendations.  Journal of Management  39 (January 2013): 48-75; Senunyeme, Emmanuel K.  Business Research Methods . Powerpoint Presentation. Regent University of Science and Technology.

Structure and Writing Style

Information about the limitations of your study is generally placed either at the beginning of the discussion section of your paper so the reader knows and understands the limitations before reading the rest of your analysis of the findings, or the limitations are outlined at the conclusion of the discussion section as an acknowledgement of the need for further study. Statements about a study's limitations should not be buried in the body [middle] of the discussion section unless a limitation is specific to something covered in that part of the paper. If this is the case, though, the limitation should be reiterated at the conclusion of the section. 

If you determine that your study is seriously flawed due to important limitations, such as an inability to acquire critical data, consider reframing it as a pilot study intended to lay the groundwork for a more complete research study in the future. Be sure, though, to specifically explain the ways that these flaws can be successfully overcome in later studies. 

But do not use this as an excuse for not developing a thorough research paper! Review the tab in this guide for developing a research topic. If serious limitations exist, it generally indicates a likelihood that your research problem is too narrowly defined or that the issue or event under study is too recent and, thus, very little research has been written about it. If serious limitations do emerge, consult with your professor about possible ways to overcome them or how to reframe your study. 

When discussing the limitations of your research, be sure to:  

Describe each limitation in detailed but concise terms; 

Explain why each limitation exists; 

Provide the reasons why each limitation could not be overcome using the method(s) chosen to gather the data [cite to other studies that had similar problems when possible]; 

Assess the impact of each limitation in relation to the overall findings and conclusions of your study; and, 

If appropriate, describe how these limitations could point to the need for further research. 

Remember that the method you chose may be the source of a significant limitation that has emerged during your interpretation of the results [for example, you didn't ask a particular question in a survey that you later wish you had]. If this is the case, don't panic. Acknowledge it and explain how applying a different or more robust methodology might address the research problem more effectively in any future study. An underlying goal of scholarly research is not only to prove what works, but to demonstrate what doesn't work or what needs further clarification. 

Brutus, Stéphane et al. Self-Reported Limitations and Future Directions in Scholarly Reports: Analysis and Recommendations.  Journal of Management  39 (January 2013): 48-75; Ioannidis, John P.A. Limitations are not Properly Acknowledged in the Scientific Literature. Journal of Clinical Epidemiology 60 (2007): 324-329; Pasek, Josh.  Writing the Empirical Social Science Research Paper: A Guide for the Perplexed . January 24, 2012. Academia.edu;  Structure: How to Structure the Research Limitations Section of Your Dissertation . Dissertations and Theses: An Online Textbook. Laerd.com;  What Is an Academic Paper?  Institute for Writing Rhetoric. Dartmouth College; Writing the Experimental Report: Methods, Results, and Discussion. The Writing Lab and The OWL. Purdue University.

Writing Tip

Don't Inflate the Importance of Your Findings!    After all the hard work and long hours devoted to writing your research paper, it is easy to get carried away with attributing unwarranted importance to what you’ve done. We all want our academic work to be viewed as excellent and worthy of a good grade, but it is important that you understand and openly acknowledge the limitations of your study. Inflating the importance of your study's findings in an attempt to hide its flaws is a big turn off to your readers. A measure of humility goes a long way! 

Another Writing Tip

Negative Results are Not a Limitation! 

Negative evidence refers to findings that unexpectedly challenge rather than support your hypothesis. If you didn't get the results you anticipated, it may mean your hypothesis was incorrect and needs to be reformulated, or perhaps you have stumbled onto something unexpected that warrants further study. Moreover, the absence of an effect may be very telling in many situations, particularly in experimental research designs. In any case, your results may be of importance to others even though they did not support your hypothesis. Do not fall into the trap of thinking that results contrary to what you expected is a limitation to your study. If you carried out the research well, they are simply your results and only require additional interpretation. 

Yet Another Writing Tip

A Note about Sample Size Limitations in Qualitative Research 

Sample sizes are typically smaller in qualitative research because, as the study goes on, acquiring more data does not necessarily lead to more information. This is because one occurrence of a piece of data, or a code, is all that is necessary to ensure that it becomes part of the analysis framework. However, it remains true that sample sizes that are too small cannot adequately support claims of having achieved valid conclusions and sample sizes that are too large do not permit the deep, naturalistic, and inductive analysis that defines qualitative inquiry. Determining adequate sample size in qualitative research is ultimately a matter of judgment and experience in evaluating the quality of the information collected against the uses to which it will be applied, and the particular research method and purposeful sampling strategy employed. If the sample size is found to be a limitation, it may reflect your judgement about the methodological technique chosen [e.g., single life history study versus focus group interviews] rather than the number of respondents used. 

Huberman, A. Michael and Matthew B. Miles. Data Management and Analysis Methods. In Handbook of Qualitative Research. Norman K. Denzin and Yvonna S. Lincoln, eds. (Thousand Oaks, CA: Sage, 1994), pp. 428-444.

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Limited by our limitations

Affiliations.

• 1 Medical School, University of Michigan, Ann Arbor, MI, USA. [email protected].
• 2 Medical School, University of Michigan, Ann Arbor, MI, USA.
• PMID: 31347033
• PMCID: PMC6684501
• DOI: 10.1007/s40037-019-00530-x

Study limitations represent weaknesses within a research design that may influence outcomes and conclusions of the research. Researchers have an obligation to the academic community to present complete and honest limitations of a presented study. Too often, authors use generic descriptions to describe study limitations. Including redundant or irrelevant limitations is an ineffective use of the already limited word count. A meaningful presentation of study limitations should describe the potential limitation, explain the implication of the limitation, provide possible alternative approaches, and describe steps taken to mitigate the limitation. This includes placing research findings within their proper context to ensure readers do not overemphasize or minimize findings. A more complete presentation will enrich the readers' understanding of the study's limitations and support future investigation.

Keywords: Limitations; Research.

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• Limitations In Research
• Writing guide

How to Organize Limitations of a Research Study

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When completing a study or any other important work, there are different details that you should include to present its comprehensive and clear description. Sometimes you might even need to hire a thesis writer to help you with the whole writing process. Don’t underrate the section with limitations in research. It plays a big role in the entire process. Some students find it difficult to write this part, while others are reluctant to include it in their academic papers. Don’t underestimate the significance of limitations in research to provide readers with an accurate context of your work and enough data to evaluate the impact and relevance of your results. What is the best way to go about them? Keep reading to find out more.

What are the Limitations of a Study (Research)?

Every research has its limitations. These limitations can appear due to constraints on methodology or research design. Needless to say, this may impact your whole study or research paper. Most researchers prefer to not discuss their study limitations because they think it may decrease the value of their paper in the eyes of the audience.

Remember that it’s quite important to show your study limitations to your audience (other researchers, editors of journals, and public readers). You need to notice that you know about these limitations and about the impact they may have. It’s important to give an explanation of how your research limitations can affect the conclusions and thoughts drawn from your research. 

In this guide, you can read useful tips on how to write limitations on your future research. Read great techniques on making a proper limitations section and see examples to make sure you have got an idea of writing your qualitative research limitations. You need to understand that even if limitations show the weaknesses of your future research, including them in your study can make your paper strengthen because you show all the problems before your readers will discover them by themselves. 

Apart from this, when the author points out the study limitations, it means that you have researched all the weak sides of your study and you understand the topic deeply. Needless to say, all the studies have their limitations even if you know how to make research design properly. When you’re honest with your readers, it can impress people much better than ignoring limitations at all.

Why and Where to Include Limitations in My Research Paper

Every research has certain limitations, and it’s completely normal, but you need to minimize their range of scope in the process. Provide your acknowledgment of them in the conclusion. Identify and understand potential shortcomings in your work.

When discussing limitations in research, explain how they impact your findings because creating their short list or description isn’t enough. Your research may have many limitations. Your basic goal is to discuss the ones that relate to the research questions that you choose for a specific academic assignment.

Limitations of your qualitative research can become clear to your readers even before they start to read your study. Sometimes, people can see the limitations only when they have viewed the whole document. You have to present your study limitations clearly in the discussion section of a researh paper . This is the final part of your work where it’s logical to place the limitations section. You should write the limitations at the very beginning of this paragraph, just after you have highlighted the strong sides of the research methodology. When you discuss the limitations before the findings are analyzed, it will help to see how to qualify and apply these findings in future research.

Common Limitations of the Researchers

Limitations related to the researcher must also be written and shown to readers. You have to provide suggestions on decreasing these limitations in both your and future studies.

Limited Access to Information 

Your study may involve some organizations and people in the research, and sometimes you may get problems with access to these organizations. Due to this, you need to redesign and rewrite your study. You need to explain the cause of limited access to your readers.

Time Limits

Needless to say, all the researchers have their deadlines when they need to complete their studies. Sometimes, time constraints can affect your research negatively. If this happened, you need to acknowledge it and mention a need for future research to solve the main problem. 

Conflicts on Biased Views and Personal Issues

Some researchers can have biased views because of their cultural background or personal views. Needless to say, it can affect the research. Apart from this, researchers with biased views can choose only those results and data that support their main arguments. If you want to avoid this problem, pay your attention to the problem statement and proper data gathering.

Different types

Before you start your study or work, keep in mind that there are specific limitations to what you test or possible research results. What are their types? There are different types that students may encounter and they all have unique features, including:

• Research design limitations,
• Impact limitations,
• Data or statistical limitations.

1. Research design limitations

Specific constraints on your population research or available procedures may affect the final outcomes or results that you obtain.

2. Impact limitations?

Even if your research has excellent stats and a strong design, it may suffer from the impact of such factors as:

• The field is conductive to incremental findings,
• Being too population-specific.
• A strong regional focus.

3. Data or statistical limitations

In some cases, it’s impossible to collect enough data or enrollment is very difficult, and all that under-powers your research results. They may stem from your study design. They produce more issues in interpreting your findings.

How to structure your research limitations correctly

There are strict rules to structure this section of your academic paper where you need to justify and explain its potential weaknesses. Take these basic steps to end up with a well-structured section:

• Announce to identify your research limitations and explain their importance,
• Reflect to provide the necessary depth, explain their nature, and justify your study choices,
• Look forward to suggest how it’s possible to overcome them in the future.

They walk your readers through this section. You need them to make it clear to your target audience that you recognize potential weaknesses in your work, understand them, and can point effective solutions.

How to set your research limitations?

No one is perfect. It means that your work isn’t beyond possible flaws, but you need to use them as a great opportunity to overcome new challenges and improve your knowledge. In a typical academic paper, research limitations can relate to these points:

• Formulation of your objectives and aims,
• Implementation of your data collection methods,
• Sample sizes,
• Lack of previous studies in your chosen area,
• The scope of discussions.

Learn to determine them in each one.

Formulation of your objectives and aims

Your work has certain shortcomings if you formulate objectives and aims in a very broad manner. What to do in this case? Specify effective methods or ways to narrow your formulation of objectives and aims to increase the level of your study focus.

Implementation of your data collection methods

If you don’t have a lot of experience in collecting primary data, there’s a certain risk that the implementation of your methods has flaws. It’s necessary to acknowledge that.

What are sample sizes?

They depend on the nature of your chosen problem and their significance is bigger in quantitative studies, unlike the qualitative ones. If your sample size is very small, statistical tests will fail to identify important relationships or connections within a particular data set. How to solve this problem? State that other researchers need to base the same study on a larger sample size to end up with more accurate results.

Lacking previous studies in the same field

A literature review is a key step in any scientific work because it helps students determine the scope of existing studies in the chosen area. Why should you use the literature review findings? They are a basic foundation for any researcher who must use them to achieve a set of specific objectives or aims. What if there are no previous works? You may face this challenge if you choose an evolving or current problem for your study or if it’s very narrow.

Scope of discussions

Feel free to include this point as a shortcoming of your work, no matter what your chosen area is. Why? The main reason is that you don’t have long years of experience in writing scientific papers or completing complex studies. That’s why the depth and scope of your discussions can be compromised in different levels compared to scholars with a lot of expertise. Include certain points from limitations in research. Use them as suggestions for the future.

Concluding thoughts

Any research suffers from specific limitations that range from common flaws to serious problems in design or methodology. The ability to set these shortcomings plays a huge role in writing a successful academic paper and earning good grades. What if you lack it? Turn to our professional thesis writers and get their expert consultation on thesis or research paper.

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Limitations of a Study: The Complete Guide

Research limitations make most studies imperfect. At its core, the research aims to investigate a specific question or questions about a topic. However, some things can hinder your ability to investigate the question or questions extensively. While this can make achieving your goals challenging, it enables you to point areas that require further studies.

That’s why you should demonstrate how future studies can provide answers to your unanswered questions if you encounter study limitations that affect your findings. Presenting the limitations of a study properly shows the readers that you understand your research problem.

After presenting your research findings, your assessment committee wants to see that you did your work professionally. And presenting limitations in a study shows that you carefully thought about your study problem and performed a review of the available literature while analyzing your preferred methods.

What Are Limitations in Research?

Well, limitations mean anything that might affect the generalizability or reliability of the outcomes of an experiment or a study. And this can relate to research design, like your approach or methods. It can also be something to do with how you carried out your research, like running out of resources or time before completing the study.

Either way, students should include their limitations when writing up their studies. In most cases, researchers include limitations in their analysis and discussions. But different schools can provide varying guidelines on how to include limitations in a research paper. Therefore, seek advice from your educator or check your writing style guide to know where to include the limitations of a study when writing a dissertation.

Common Study Limitations

Each study can have unique limitations. However, most students encounter common study limitations when writing academic papers. Here are some of the most common limitations you’re likely to encounter when writing your academic papers.

Sample profile or size: Most researchers encounter sampling as a limitation for their studies. That’s because they have difficulties finding the right sample with the necessary characteristics and size parameters. And this hinders the generalizability of their study results. Also, different sampling techniques are prone to bias and errors. And this can influence the study outcomes. In some cases, researchers have difficulties selecting their samples and opt to pick their participants selectively. Some researchers can even include irrelevant subjects in their general pool to hit their preferred sample size. Availability of previous research or information: Theoretical concepts or previous knowledge form the basis of studies on specific topics. And this provides a sound foundation on which a researcher can develop a research problem for their investigation and a design. However, a topic can be relatively specific or very progressive. In that case, the lack of or inadequate knowledge and previous studies can limit the analysis scope. And this can cause inaccuracies in the arguments or present a significant error margin in several methodologies and research aspects. Methodology errors: Modern research complexity can cause potential methodology limitations. In most cases, these research limitations relate to how the researchers collect and analyze data. That’s because these aspects can influence the outcomes of a study. Researchers use different techniques to gather data. While these techniques may suit a study design, they can present limitations in terms of inappropriate detail levels, distractions, and privacy. Bias: Bias is a potential limitation whose effects can influence the outcome of every study. However, a researcher can avoid this limitation by eliminating prejudiced or emotional attitudes towards their topic and conflict of interest. Researchers should also establish an oversight level by referring to peer-review procedures or an ethics committee. Bias is an inherent trait for human beings. Even the most objective people exhibit a bias to some extent. Nevertheless, a researcher should remain objective while trying to control potential inaccuracies or bias during the research process.

A researcher may not have control over the limitation of study. However, the limitation can be the condition, influence, or shortcoming that places restrictions on their conclusions or methodology. Therefore, researchers should mention all limitations that can influence their results.

Limitations of the Study Example

The purpose of most studies is to confirm or establish facts, reaffirm a previous study’s outcomes, solve current or new issues, develop a new theory, or support theorems. Research should also enable experts to develop knowledge on specific subjects. And people research different subjects, depending on their interests. However, researchers experience limitations of quantitative research and qualitative research. Here are the most common limitations in research.

Lack or inadequate interactions: Researchers might lack adequate interactions with government institutions and businesses. Consequently, they do not tap a substantial data amount. Researchers should arrange interaction programs with other establishments. That way, they can identify issues that warrant investigation and the necessary data for conducting research, as well as, the benefits of their studies. Overlapping studies can lead fritter resources away or duplicate the findings. Appropriate revision and compilation at regular intervals can solve this problem. Costly publishing: After researching a topic, a researcher should find ways to publish their findings. However, international journals cost a lot of money to publish a study. And this can discourage a researcher from publishing their work. For instance, a study involving females only or carried out in a specific town can have limitations like sample size, gender, and location. What’s more, the entire study could be limited to the researcher’s perception. Lack of or inadequate training: The research process doesn’t have a systematic methodology. Many researchers do not understand the research method when carrying out their work. Consequently, most researchers experience methodological limitations. Essentially, most researchers replicate the methodologies of similar studies. Even some research guides don’t explain the methodologies accurately. And this can limit the outcome of some studies. Lack of code of conduct: Researchers don’t have a code of conduct. And this causes inter-university and inter-departmental rivalries. Library functioning and management are not adequate in most places. Consequently, some researchers spend a lot of energy and time tracing the necessary books, reports, and journals for their studies. Such energy and time can be spent tracing relevant materials. Lack of confidence: The lack of confidence is among the most common limitations of research studies because company managers think that a researcher can misuse the data they disclose to them. Consequently, they don’t want to reveal their business information. And this can affect studies, yet data from researchers can help the same institutions. Therefore, organizations and researchers should implement confidence-building strategies to encourage companies to share data, knowing that researchers will use it productively.

Why Write the Limitations of a Study?

When writing a research paper or a thesis, some people think including study limitations is counterintuitive. That’s particularly the case for researchers that experienced something wrong. However, mentioning the limitations of your study is imperative for the following reasons.

• It tells the readers that you understand that no study lacks some limitations, and you took the time to analyze your work critically.
• It provides opportunities for further studies.
• It enables you to discuss the impacts of the limitations on your analysis and how future studies can address the challenges you encountered if granted a chance to do the study again.
• It presents your study as a transparent undertaking, making the results useful and credible for other people.

Most professors spot problems with the students’ work even if they don’t mention them. Consequently, embracing the limitations of your study and including them in your analysis is the best approach. Leaving out the limitations of research or vital aspects of a study can be detrimental to the entire study field. That’s because it can establish a potentially fallacious and incomplete depiction of the study.

In the academic world, players expect researchers to include the limitations of their works. And this includes a section that demonstrates a holistic and comprehensive understanding of a topic and research process by the author. Discussing limitations is a learning process for assessing the magnitude while critically evaluating the extenuating effect of the stated limitations.

Stating the limitations of a study also improves the validity and quality of future studies. And this includes limitations whose basis is the transparency principle in scientific research, whose purpose is to promote further progress while maintaining mutual integrity in similar studies.

How to Write Study Limitations

When writing your research limitations, do it in a way that demonstrates your understanding of the core concepts of confounding, analytical self-criticism, and bias. Highlighting every limitation might not be necessary. However, include every limitation with a direct impact on your research problem or study results.

Present your thought process as a researcher and explain the pros and cons of your decisions. Also, explain circumstances that may have led to a research limitation. Here’s how you should structure your limitations.

• Identification and description of the limitation: Use professional terminology to identify and describe the limitation. Also, include all necessary accompanying definitions. The limitation explanation should be precise and brief to ensure that the audience can easily understand the issue. Additionally, make sure that your audience can follow your thought pattern.
• Outline the possible impact or influence of the limitation: Explain to your readers how the limitation may have affected or influenced your study. And this comprises elements like the impact’s magnitude, occurrence likelihood, and the general direction the specific limitation could have driven your findings. Researchers generally accept that a limitation can have a more profound influence on a study than others. Therefore, highlight the effect or influence of a limitation to help readers decide on the issues to consider while examining your topic. And this is vital because a limitation whose value bias is null is less dangerous.
• Discuss alternative approaches to limitations: You can also discuss alternative ways to approach the limitations of your research question. However, the researcher should support the methodology or approach they selected in their study. Also, a research paper should explain why the study context warranted the methodology or approach, regardless of the limitation’s nature. Some researchers even provide persuasive evidence while discussing alternative decisions to some extent. And this shows thought transparency while reassuring readers that the researcher chose the best approach, despite the possible laminations.
• Description of the techniques for minimizing risks: Any limitation in research comes with some risks. Therefore, a researcher should describe possible techniques for minimizing the potential risk from the stated limitations. Such techniques can include a reference of previous studies and suggestions for improving data analysis and research design.

Don’t forget that acknowledging your study limitations provides a chance to suggest the direction for further studies. Therefore, connect the limitations of your study to the suggestions you make for further research. Also, explain how your study can make the unanswered questions more focused.

Also, acknowledging the limitation of the study enables you to demonstrate to the professor that you have critically thought about your research problem and understood the importance of the already-published literature. What’s more, it shows that you’ve carefully assessed the methods for studying your study problem. In research, a key objective is to discover new knowledge while confronting assumptions as you explore what others might not know.

Writing limitations should be a subjective process. That’s because you must analyze the impacts of the limitations and include them in your paper. In this section, don’t include the key weaknesses only. Instead, highlight the magnitude of the limitations of your research. And doing this requires you to demonstrate your study’s validity. Show the readers how the limitations have impacted your study outcomes and conclusions. Thus, writing the limitations section of your paper requires an overall, critical interpretation and appraisal of the impact. Essentially, this section should tell the readers why the problems with methods, errors, validity, and other limitations matter and to what extent.

Practical Tips for Writing Research Limitations

When writing a research paper, include information about your study’s limitations at the beginning of the discussion section. That way, your readers can understand your study limitations before delving into the deeper analysis. In some cases, authors bring out limitations when concluding their research discussion and highlighting the essence of further study on the subject. Here are practical tips to help you write the limitations of your study more effectively.

• Check some examples of limitations in research first: To understand the best way to include or present the limitations of your study, check how other authors do it. The internet is awash with good sample papers with a section for limitations. Checking such samples can help you write a limitations section for your academic paper.
• Include essential limitations only: Don’t come up with a list of limitations in your research paper. That’s because doing so can discredit the entire research project. Instead, highlight up to 3 limitations whose influence on your work was the highest. Also, explain how each of the limitations affected your work and research findings.
• Be brief and direct to the point: Identify the limitation, what caused it, and its impact on your research. Don’t expound on the limitation beyond this because the limitation section should be a small part of your paper.
• Be sincere: Don’t make up some lies or disguise your research limitations. That’s because doing so could prove you aren’t prepared. Therefore, be true and sincere with the audience. As you might see in good examples of study limitations, this section tells the audience what could be different or better.
• Explain what caused the limitations of your study: Your audience should have an easy time identifying the reason for the limitations. Therefore, make sure that you have explained everything correctly. Telling the readers about a limiting factor without explaining it can give them the impression that you’re outside your research project.
• Make suggestions for further studies: An ideal way for reversing points that other researchers can explore is to suggest future research paths. Your study could have failed in certain aspects. Maybe you didn’t achieve your expected results. However, it can prompt other researchers to take different directions in their future studies. Also, explain how other researchers can overcome the limitations you encountered in your study. You can even demonstrate why additional studies on the topic or subject are essential.
• Don’t confuse negative results with limitations: If your study brings out negative results, don’t confuse them for limitations. What negative outcomes mean is that you should support your hypothesis instead of opposing it. Perhaps, you can check sample limitations to understand what qualifies as a limitation. However, you can reformulate your hypothesis if you get negative results. Even when you stumble onto something you didn’t expect, don’t highlight it as a limitation.

Final Thoughts

When working on the limitations section of a research paper, be precise and clear. If writing this section becomes challenging, follow the tips shared in this article or seek assistance. That way, you can impress your educator by highlighting the limitations of your study properly.

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A systematic literature review of modalities, trends, and limitations in emotion recognition, affective computing, and sentiment analysis.

1. Introduction

2. methodology, 2.1. research questions, 2.2. search process, 2.2.1. search terms, 2.2.2. inclusion and exclusion criteria, 2.2.3. quality assessment, 2.2.4. data extraction, 3.1. overview, 3.2. unimodal data approaches, 3.2.1. unimodal physical approaches, 3.2.2. unimodal speech data approaches.

• Several articles mention the use of transfer learning for speech emotion recognition. This technique involves training models on one dataset and applying them to another. This can improve the efficiency of emotion recognition across different datasets.
• Some articles discuss multitask learning models, which are designed to simultaneously learn multiple related tasks. In the context of speech emotion recognition, this approach may help capture commonalities and differences across different datasets or emotions.
• Data augmentation techniques are mentioned in multiple articles, which involve generating additional training data from existing data, which can improve model performance and generalization.
• Attention mechanisms are a common trend for improving emotion recognition. Attention models allow the model to focus on specific features or segments of the input data that are most relevant for recognizing emotions, such as in multi-level attention-based approaches.
• Many articles discuss the use of deep learning models, such as convolutional neural networks (CNNs), recurrent neural networks (RNNs), and some variants like “Two-Stage Fuzzy Fusion Based-Convolution Neural Network, “Deep Convolutional LSTM”, and “Attention-Oriented Parallel CNN Encoders”.
• While deep learning is prevalent, some articles explore novel feature engineering methods, such as modulation spectral features and wavelet packet information gain entropy, to enhance emotion recognition.
• From the list of articles on unimodal emotion recognition through speech, 7.14% address the challenge of recognizing emotions across different datasets or corpora. This is an important trend for making emotion recognition models more versatile.
• A few articles focus on making emotion recognition models more interpretable and explainable, which is crucial for real-world applications and understanding how the model makes its predictions.
• Ensemble methods, which combine multiple models to make predictions, are mentioned in several articles as a way to improve the performance of emotion recognition systems.
• Some articles discuss emotion recognition in specific contexts, such as call/contact centers, school violence detection, depression detection, analysis of podcast recordings, noisy environment analysis, in-the-wild sentiment analysis, and speech emotion segmentation of vowel-like and non-vowel-like regions. This indicates a trend toward applying emotion recognition in diverse applications.

3.2.3. Unimodal Text Data Approaches

3.2.4. unimodal physiological data approaches.

• Attention and self-attention mechanisms: These suggest that researchers are paying attention to the relevance of different parts of EEG signals for emotion recognition.
• Generative adversarial networks (GANs): Used for generating synthetic EEG data in order to improve the robustness and generalization of the models.
• Semi-supervised learning and domain transfer: Allow emotion recognition with limited datasets or datasets that are applicable to different domains, suggesting a concern for scalability and generalization of models.
• Interpretability and explainability: There is a growing interest in models that are interpretable and explainable, suggesting a concern for understanding how models make decisions and facilitating user trust in them.
• Utilization of transformers and capsule networks: Newer neural network architectures such as transformers and capsule networks are being explored for emotion recognition, indicating an interest in enhancing the modeling and representation capabilities of EEG signals.
• Although studies with a unimodal physical approach using signals different from EEG, like ECG, EDA, HR, and PPG, are still scarce, these can provide information about the cardiovascular system and the body’s autonomic response to emotions. Their limitations are that they may not be as specific or sensitive in detecting subtle or changing emotions. Noise and artifacts, such as motion, can affect the quality of these signals in practical situations and can be influenced by non-emotional factors, such as physical exercise and fatigue. Various studies explore the utilization of ECG and PPG signals for emotion recognition and stress classification. Techniques such as CNNs, LSTMs, attention mechanisms, self-supervised learning, and data augmentation are employed to analyze these signals and extract meaningful features for emotion recognition tasks. Bayesian deep learning frameworks are utilized for probabilistic modeling and uncertainty estimation in emotion prediction from HB data. These approaches aim to enhance human–computer interaction, improve mental health monitoring, and develop personalized systems for emotion recognition based on individual user characteristics.

3.3. Multi-Physical Data Approaches

• Most studies employ CNNs and RNNs, while others utilize variations of general neural networks, such as spiking neural networks (SNN) and tree-based neural networks. SNNs represent and transmit information through discrete bursts of neuronal activity, known as “spikes” or “pulses”, unlike conventional neural networks, which process information in continuous values. Additionally, several studies leverage advanced analysis models such as the stacked ensemble model and multimodal fusion models, which focus on integrating diverse sources of information to enhance decision-making. Transfer learning models and hybrid attention networks aim to capitalize on knowledge from related tasks or domains to improve performance in a target task. Attention-based neural networks prioritize capturing relevant information and patterns within the data. Semi-supervised and contrastive learning models offer alternative learning paradigms by incorporating both labeled and unlabeled data.
• The studies address diverse applications, including sarcasm, sentiment, and emotion recognition in conversations, financial distress prediction, performance evaluation in job interviews, emotion-based location recommendation systems, user experience (UX) analysis, emotion detection in video games, and in educational settings. This suggests that emotion recognition thorough multi-physical data analysis has a wide spectrum of applications in everyday life.
• Various audio and video signal processing techniques are employed, including pitch analysis, facial feature detection, cross-attention, and representational learning.

3.4. Multi-Physiological Data Approaches

• The fusion of physiological signals, such as EEG, ECG, PPG, GSR, EMG, BVP, EOG, respiration, temperature, and movement signals, is a predominant trend in these studies. The combination of multiple physiological signals allows for a richer representation of emotions.
• Most studies apply deep learning models, such as CNNs, RNNs, and autoencoder neural networks (AE), for the processing and analysis of these signals. Supervised and unsupervised learning approaches are also used.
• These studies focus on a variety of applications, such as emotion recognition in healthcare environments, brain–computer interfaces for music, emotion detection in interactive virtual environments, stress assessment in mobility environments for visually impaired people, among others. This indicates that emotion recognition based on physiological signals has applications in healthcare, technology, and beyond.
• Some studies focus on personalized emotion recognition, suggesting tailoring of models for each individual. This may be relevant for personalized health and wellness applications. Others focus on interactive applications and virtual environments useful for entertainment and virtual therapy.
• It is important to mention that the studies within this classification are quite limited in comparison to the previously described modalities. Although it appears that they are using similar physiological signals, the databases differ in terms of their approaches and generation methods. Therefore, there is an opportunity to establish a protocol for generating these databases, allowing for meaningful comparisons among studies.

3.5. Multi-Physical–Physiological Data Approaches

• Studies tend to combine multiple types of signals, such as EEG, facial expressions, voice signals, GSR, and other physiological data. Combining signals aims to take advantage of the complementarity of different modalities to improve accuracy in emotion detection.
• Machine learning models, in particular CNNs, are widely used in signal fusion for emotion recognition. CNN models can effectively process data from multiple modalities.
• Applications are also being explored in the health and wellness domain, such as emotion detection for emotional health analysis of people in smart environments.
• The use of standardized and widely accepted databases is important for comparing results between different studies; however, these are still limited.
• The trend towards non-intrusive sensors and wireless technology enables data collection in more natural and less intrusive environments, which facilitates the practical application of these systems in everyday environments.

4. Discussion

• Facial expression analysis approaches are currently being applied across various domains, including naturalistic settings (“in the wild”), on-road driver monitoring, virtual reality environments, smart homes, IoT and edge devices, and assistive robots. There is also a focus on mental health assessment, including autism, depression, and schizophrenia, and distinguishing between genuine and unfelt facial expressions of emotion. Efforts are being made to improve performance in processing faces acquired at a distance despite the challenges posed by low-quality images. Furthermore, there is an emerging interest in utilizing facial expression analysis in human–computer interaction (HCI), learning environments, and multicultural contexts.
• The recognition of emotions through speech and text has experienced tremendous growth, largely due to the abundance of information facilitated by advancements in technology and social media. This has enabled individuals to express their opinions and sentiments through various media, including podcast recordings, live videos, and readily available data sources such as social media platforms like Twitter, Facebook, Instagram, and blogs. Additionally, researchers have utilized unconventional sources like stock market data and tourism-related reviews. The variety and richness of these data sources indicate a wide range of segments where such emotion recognition analyses can be applied effectively.
• EEG signals continue to be a prominent modality for emotion recognition due to their highly accurate insights into emotional states. Between 2022 and 2023, studies in this field experienced exponential growth. The identified trends include utilizing EEG for enhancing human–computer interaction, recognizing emotions in various contexts such as patients with consciousness disorders, movie viewing, virtual environments, and driving scenarios. EEG is being used for detecting and monitoring mental health issues. There is also a growing focus on personalization, leading towards more individualized and user-specific emotion recognition systems, Other physiological signals, such as ECG, EDA, and HR, are also gaining attention, albeit at a slower pace.
• In the realm of multi-physical, multi-physiological, and multi-physical–physiological approaches, it is the former that appears to be laying the groundwork, as evidenced by the abundance of studies in this area. The latter two approaches, incorporating fusions with physiological signals, are still relatively scarce but seem to be paving the way for future researchers to contribute to their growth. Multimodal approaches, which integrate both physical and physiological signals, are finding diverse applications in emotion recognition. These range from healthcare systems, individual and group mood research, personality recognition, pain intensity recognition, anxiety detection, work stress detection, stress classification and security monitoring in public spaces, to vehicle security monitoring, movie audience emotion recognition, applications for autism spectrum disorder detection, music interfacing, and virtual environments.
• Bidirectional encoder representations from transformers: Used in sentiment analysis and emotion recognition from text, BERT models can understand the context of words in sentences by pre-training on a large text and then fine-tuning for specific tasks like sentiment analysis.
• CNNs: These are commonly applied in facial emotion recognition, emotion recognition from physiological signals, and even in speech emotion recognition by analyzing spectrograms.
• RNNS and variants (LSTM, GRU): These models are suited for sequential data like speech and text. LSTMs and GRUs are particularly effective in speech emotion recognition and sentiment analysis of time-series data.
• Graph convolutional networks (GCNs): Applied in emotion recognition from EEG signals and conversation-based emotion recognition, these can model relational data and capture the complex dependencies in graph-structured data, like brain connectivity patterns or conversational contexts.
• Attention mechanisms and transformers: Enhancing the ability of models to focus on relevant parts of the data, attention mechanisms are integral to models like transformers for tasks that require understanding the context, such as sentiment analysis in long documents or emotion recognition in conversations.
• Ensemble models: Combining predictions from multiple models to improve accuracy, ensemble methods are used in multimodal emotion recognition, where inputs from different modalities (e.g., audio, text, and video) are integrated to make more accurate predictions.
• Autoencoders and generative adversarial networks (GANs): For tasks like data augmentation in emotion recognition from EEG or for generating synthetic data to improve model robustness, these unsupervised learning models can learn compact representations of data or generate new data samples, respectively.
• Multimodal fusion models: In applications requiring the integration of multiple data types (e.g., speech, text, and video for emotion recognition), fusion models combine features from different modalities to capture more comprehensive information for prediction tasks.
• Transfer learning: Utilizing pre-trained models on large datasets and fine-tuning them for specific affective computing tasks, transfer learning is particularly useful in scenarios with limited labeled data, such as sentiment analysis in niche domains.
• Spatio-temporal models: For tasks that involve data with both spatial and temporal dimensions (like video-based emotion recognition or physiological signal analysis), models that capture spatio-temporal dynamics are employed, combining approaches like CNNs for spatial features and RNNs/LSTMs for temporal features.

5. Conclusions

Author contributions, institutional review board statement, informed consent statement, data availability statement, acknowledgments, conflicts of interest.

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García-Hernández, R.A.; Luna-García, H.; Celaya-Padilla, J.M.; García-Hernández, A.; Reveles-Gómez, L.C.; Flores-Chaires, L.A.; Delgado-Contreras, J.R.; Rondon, D.; Villalba-Condori, K.O. A Systematic Literature Review of Modalities, Trends, and Limitations in Emotion Recognition, Affective Computing, and Sentiment Analysis. Appl. Sci. 2024 , 14 , 7165. https://doi.org/10.3390/app14167165

García-Hernández RA, Luna-García H, Celaya-Padilla JM, García-Hernández A, Reveles-Gómez LC, Flores-Chaires LA, Delgado-Contreras JR, Rondon D, Villalba-Condori KO. A Systematic Literature Review of Modalities, Trends, and Limitations in Emotion Recognition, Affective Computing, and Sentiment Analysis. Applied Sciences . 2024; 14(16):7165. https://doi.org/10.3390/app14167165

García-Hernández, Rosa A., Huizilopoztli Luna-García, José M. Celaya-Padilla, Alejandra García-Hernández, Luis C. Reveles-Gómez, Luis Alberto Flores-Chaires, J. Ruben Delgado-Contreras, David Rondon, and Klinge O. Villalba-Condori. 2024. "A Systematic Literature Review of Modalities, Trends, and Limitations in Emotion Recognition, Affective Computing, and Sentiment Analysis" Applied Sciences 14, no. 16: 7165. https://doi.org/10.3390/app14167165

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Home News As AI Paves the Way for Healthcare Innovation, Can We Avoid the Potholes? back to News

As AI Paves the Way for Healthcare Innovation, Can We Avoid the Potholes?

Cu anschutz researcher explores ai in medicine at cctsi conference.

minute read

Jayashree Kalpathy-Cramer , PhD, used ChatGPT to create a professional bio. The artificial intelligence platform got many things right, correctly listing her recent publications, areas of research, past employers and current lab.

Then she asked it to add her undergraduate degree.

“It made that up completely.”

Kalpathy-Cramer is chief of the new Division of Artificial Medical Intelligence in the Department of Ophthalmology at the University of Colorado School of Medicine . She is also director of CCTSI’s Health Informatics at the Colorado Clinical and Translational Sciences Institute at the CU Anschutz Medical Campus. She said the more she tried to convince ChatGTP of its error, the more it “hallucinated,” making up sources that did not exist.

“Maybe it heard my voice and decided I'm from South India, and therefore that's where I went to school,” she said.

Kalpathy-Cramer shared the story with attendees of the 2024 CCTSI CU-CSU Summit . The annual conference took place Aug. 13 at CU Anschutz to explore innovations in health AI with CCTSI researchers from its affiliated campuses. Her presentation focused on the significant potential, and a few of the limitations, of AI in healthcare.

How AI models are used in research and beyond

Kalpathy-Cramer began with a survey of attendees to gauge faculty perceptions of AI. Some attendees had never used AI tools, while a larger percentage used them regularly, or even daily. Attendees said they use AI for tasks such as coding, generating research questions, and drafting letters of recommendation and that they were also aware of its limitations. Like Kalpathy-Cramer, many conference-goers said they had experienced frustration with the AI's overconfidence in plausible-sounding, yet incorrect, answers.

Kalpathy-Cramer provided a high-level snapshot of AI-focused projects within her department, using a slide deck made in collaboration with ChatGPT.

Her division, which includes about a dozen members, primarily data scientists, first created a research warehouse of data, including images, electronic health records and other data needed to train AI. These data are used to train a variety of AI algorithms. The researchers work on developing novel AI methods as well as the application novel AI algorithms to many clinical questions. The team is especially focused on issues such as bias and fairness and ensuring that the algorithms are suitable for patient care.

Building an AI model for retinopathy of prematurity

The department has developed AI models for imaging related to retinopathy of prematurity (ROP), a disease that primarily affects low-birthweight or premature babies. ROP is a leading cause of preventable blindness worldwide, particularly in low- and middle-income countries such as India.

Oxygen-management issues affecting premature infants increase their risk for ROP. While treatment is available if diagnosed in time, many regions lack sufficient pediatric ophthalmologists for proper diagnosis and treatment. ROP is diagnosed through imaging of retinal blood vessels, classified on a three-level severity scale. The challenge is to make AI effective in this context to improve access to care.

Kalpathy-Cramer also explored studies such as the HPV-automated visual evaluation (PAVE) for advancing cervical cancer prevention and the National Cancer Institute Cancer Moonshot research initiative to demonstrate how AI is already being used to improve access, quality, safety and efficiency of care.

Bringing together a community to address AI concerns

Kalpathy-Cramer emphasized the need for researchers to collaborate as a community to address the many questions surrounding the effective and safe use of AI in healthcare.

One challenge is overcoming bias. She used the example of how AI models can predict self-reported race with great accuracy by looking at chest X-ray s .

“Humans can’t do that,” she said. “AI is already encoding this information. What is it looking at? We have to be aware of the many ways bias can creep in from data generation and model building.”

She also talked about generalization.  

“The models tend to be brittle. They work on the device they were trained on but if there’s a software update or you put it on a different device, the model falls apart. And the hard part is you don't know that it's not working.”

It's also impossible to know if a model has stopped working if a human isn’t able to validate the AI, which raises ethical concerns.

“ AI can predict the likelihood of getting breast cancer five years in the future with very high accuracy, yet a human eye can’t see what it sees. Do we deploy that? Because maybe it helps people. But on the other hand, if no human can validate the risk, how do we know it's safe?”  

Kalpathy-Cramer also raised practical concerns related to the development and deployment of AI in healthcare. Issues like payment, reimbursement and liability must be considered when deciding to use AI.  

She concluded the talk with an AI-generated image symbolizing the intersection of data, AI and people in healthcare. She laughed at a spelling error in the image but emphasized that, from the perspective of those working in AI, there's much to be excited about.

“We really do think it has the ability to improve care, improve access to care, improve quality and safety, and make things more efficient, less expensive and safer,” she said. “But there are also lots of potholes.”

Topics: Research , Patient Care , Artificial Intelligence (AI)

Jayashree Kalpathy-Cramer, PhD

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Organizing Academic Research Papers: Limitations of the Study

• Purpose of Guide
• Design Flaws to Avoid
• Glossary of Research Terms
• Narrowing a Topic Idea
• Broadening a Topic Idea
• Extending the Timeliness of a Topic Idea
• Academic Writing Style
• Choosing a Title
• Making an Outline
• Paragraph Development
• Executive Summary
• Background Information
• The Research Problem/Question
• Theoretical Framework
• Citation Tracking
• Content Alert Services
• Evaluating Sources
• Primary Sources
• Secondary Sources
• Tertiary Sources
• What Is Scholarly vs. Popular?
• Qualitative Methods
• Quantitative Methods
• Using Non-Textual Elements
• Limitations of the Study
• Common Grammar Mistakes
• Avoiding Plagiarism
• Footnotes or Endnotes?
• Further Readings
• Annotated Bibliography
• Dealing with Nervousness
• Using Visual Aids
• Grading Someone Else's Paper
• How to Manage Group Projects
• Multiple Book Review Essay
• Reviewing Collected Essays
• About Informed Consent
• Writing Field Notes
• Writing a Policy Memo
• Writing a Research Proposal
• Acknowledgements

The limitations of the study are those characteristics of design or methodology that impacted or influenced the application or interpretation of the results of your study. They are the constraints on generalizability and utility of findings that are the result of the ways in which you chose to design the study and/or the method used to establish internal and external validity.

Importance of...

Always acknowledge a study's limitations. It is far better for you to identify and acknowledge your study’s limitations than to have them pointed out by your professor and be graded down because you appear to have ignored them.

Keep in mind that acknowledgement of a study's limitations is an opportunity to make suggestions for further research. If you do connect your study's limitations to suggestions for further research, be sure to explain the ways in which these unanswered questions may become more focused because of your study.

Acknowledgement of a study's limitations also provides you with an opportunity to demonstrate to your professor that you have thought critically about the research problem, understood the relevant literature published about it, and correctly assessed the methods chosen for studying the problem. A key objective of the research process is not only discovering new knowledge but also to confront assumptions and explore what we don't know.

Claiming limitiations is a subjective process because you must evaluate the impact of those limitations . Don't just list key weaknesses and the magnitude of a study's limitations. To do so diminishes the validity of your research because it leaves the reader wondering whether, or in what ways, limitation(s) in your study may have impacted the findings and conclusions. Limitations require a critical, overall appraisal and interpretation of their impact. You should answer the question: do these problems with errors, methods, validity, etc. eventually matter and, if so, to what extent?

Structure: How to Structure the Research Limitations Section of Your Dissertation . Dissertations and Theses: An Online Textbook. Laerd.com.

Descriptions of Possible Limitations

All studies have limitations . However, it is important that you restrict your discussion to limitations related to the research problem under investigation. For example, if a meta-analysis of existing literature is not a stated purpose of your research, it should not be discussed as a limitation. Do not apologize for not addressing issues that you did not promise to investigate in your paper.

Here are examples of limitations you may need to describe and to discuss how they possibly impacted your findings. Descriptions of limitations should be stated in the past tense.

Possible Methodological Limitations

• Sample size -- the number of the units of analysis you use in your study is dictated by the type of research problem you are investigating. Note that, if your sample size is too small, it will be difficult to find significant relationships from the data, as statistical tests normally require a larger sample size to ensure a representative distribution of the population and to be considered representative of groups of people to whom results will be generalized or transferred.
• Lack of available and/or reliable data -- a lack of data or of reliable data will likely require you to limit the scope of your analysis, the size of your sample, or it can be a significant obstacle in finding a trend and a meaningful relationship. You need to not only describe these limitations but to offer reasons why you believe data is missing or is unreliable. However, don’t just throw up your hands in frustration; use this as an opportunity to describe the need for future research.
• Lack of prior research studies on the topic -- citing prior research studies forms the basis of your literature review and helps lay a foundation for understanding the research problem you are investigating. Depending on the currency or scope of your research topic, there may be little, if any, prior research on your topic. Before assuming this to be true, consult with a librarian! In cases when a librarian has confirmed that there is a lack of prior research, you may be required to develop an entirely new research typology [for example, using an exploratory rather than an explanatory research design]. Note that this limitation can serve as an important opportunity to describe the need for further research.
• Measure used to collect the data -- sometimes it is the case that, after completing your interpretation of the findings, you discover that the way in which you gathered data inhibited your ability to conduct a thorough analysis of the results. For example, you regret not including a specific question in a survey that, in retrospect, could have helped address a particular issue that emerged later in the study. Acknowledge the deficiency by stating a need in future research to revise the specific method for gathering data.
• Self-reported data -- whether you are relying on pre-existing self-reported data or you are conducting a qualitative research study and gathering the data yourself, self-reported data is limited by the fact that it rarely can be independently verified. In other words, you have to take what people say, whether in interviews, focus groups, or on questionnaires, at face value. However, self-reported data contain several potential sources of bias that should be noted as limitations: (1) selective memory (remembering or not remembering experiences or events that occurred at some point in the past); (2) telescoping [recalling events that occurred at one time as if they occurred at another time]; (3) attribution [the act of attributing positive events and outcomes to one's own agency but attributing negative events and outcomes to external forces]; and, (4) exaggeration [the act of representing outcomes or embellishing events as more significant than is actually suggested from other data].

Possible Limitations of the Researcher

• Access -- if your study depends on having access to people, organizations, or documents and, for whatever reason, access is denied or otherwise limited, the reasons for this need to be described.
• Longitudinal effects -- unlike your professor, who can literally devote years [even a lifetime] to studying a single research problem, the time available to investigate a research problem and to measure change or stability within a sample is constrained by the due date of your assignment. Be sure to choose a topic that does not require an excessive amount of time to complete the literature review, apply the methodology, and gather and interpret the results. If you're unsure, talk to your professor.
• Cultural and other type of bias -- we all have biases, whether we are conscience of them or not. Bias is when a person, place, or thing is viewed or shown in a consistently inaccurate way. It is usually negative, though one can have a positive bias as well. When proof-reading your paper, be especially critical in reviewing how you have stated a problem, selected the data to be studied, what may have been omitted, the manner in which you have ordered events, people, or places and how you have chosen to represent a person, place, or thing, to name a phenomenon, or to use possible words with a positive or negative connotation. Note that if you detect bias in prior research, it must be acknowledged and you should explain what measures were taken to avoid perpetuating bias.
• Fluency in a language -- if your research focuses on measuring the perceived value of after-school tutoring among Mexican-American ESL [English as a Second Language] students, for example, and you are not fluent in Spanish, you are limited in being able to read and interpret Spanish language research studies on the topic. This deficiency should be acknowledged.

Brutus, Stéphane et al. Self-Reported Limitations and Future Directions in Scholarly Reports: Analysis and Recommendations. Journal of Management 39 (January 2013): 48-75; Senunyeme, Emmanuel K. Business Research Methods . Powerpoint Presentation. Regent University of Science and Technology.

Structure and Writing Style

Information about the limitations of your study are generally placed either at the beginning of the discussion section of your paper so the reader knows and understands the limitations before reading the rest of your analysis of the findings, or, the limitations are outlined at the conclusion of the discussion section as an acknowledgement of the need for further study. Statements about a study's limitations should not be buried in the body [middle] of the discussion section unless a limitation is specific to something covered in that part of the paper. If this is the case, though, the limitation should be reiterated at the conclusion of the section.

If you determine that your study is seriously flawed due to important limitations , such as, an inability to acquire critical data, consider reframing it as a pilot study intended to lay the groundwork for a more complete research study in the future. Be sure, though, to specifically explain the ways that these flaws can be successfully overcome in later studies.

But, do not use this as an excuse for not developing a thorough research paper! Review the tab in this guide for developing a research topic . If serious limitations exist, it generally indicates a likelihood that your research problem is too narrowly defined or that the issue or event under study  is too recent and, thus, very little research has been written about it. If serious limitations do emerge, consult with your professor about possible ways to overcome them or how to reframe your study.

When discussing the limitations of your research, be sure to:

• Describe each limitation in detailed but concise terms;
• Explain why each limitation exists;
• Provide the reasons why each limitation could not be overcome using the method(s) chosen to gather the data [cite to other studies that had similar problems when possible];
• Assess the impact of each limitation in relation to  the overall findings and conclusions of your study; and,
• If appropriate, describe how these limitations could point to the need for further research.

Remember that the method you chose may be the source of a significant limitation that has emerged during your interpretation of the results [for example, you didn't ask a particular question in a survey that you later wish you had]. If this is the case, don't panic. Acknowledge it, and explain how applying a different or more robust methodology might address the research problem more effectively in any future study. A underlying goal of scholarly research is not only to prove what works, but to demonstrate what doesn't work or what needs further clarification.

Brutus, Stéphane et al. Self-Reported Limitations and Future Directions in Scholarly Reports: Analysis and Recommendations. Journal of Management 39 (January 2013): 48-75; Ioannidis, John P.A. Limitations are not Properly Acknowledged in the Scientific Literature. Journal of Clinical Epidemiology 60 (2007): 324-329; Pasek, Josh. Writing the Empirical Social Science Research Paper: A Guide for the Perplexed . January 24, 2012. Academia.edu; Structure: How to Structure the Research Limitations Section of Your Dissertation . Dissertations and Theses: An Online Textbook. Laerd.com; What Is an Academic Paper? Institute for Writing Rhetoric. Dartmouth College; Writing the Experimental Report: Methods, Results, and Discussion. The Writing Lab and The OWL. Purdue University.

Writing Tip

Don't Inflate the Importance of Your Findings! After all the hard work and long hours devoted to writing your research paper, it is easy to get carried away with attributing unwarranted importance to what you’ve done. We all want our academic work to be viewed as excellent and worthy of a good grade, but it is important that you understand and openly acknowledge the limitiations of your study. Inflating of the importance of your study's findings in an attempt hide its flaws is a big turn off to your readers. A measure of humility goes a long way!

Another Writing Tip

Negative Results are Not a Limitation!

Negative evidence refers to findings that unexpectedly challenge rather than support your hypothesis. If you didn't get the results you anticipated, it may mean your hypothesis was incorrect and needs to be reformulated, or, perhaps you have stumbled onto something unexpected that warrants further study. Moreover, the absence of an effect may be very telling in many situations, particularly in experimental research designs. In any case, your results may be of importance to others even though they did not support your hypothesis. Do not fall into the trap of thinking that results contrary to what you expected is a limitation to your study. If you carried out the research well, they are simply your results and only require additional interpretation.

Yet Another Writing Tip

A Note about Sample Size Limitations in Qualitative Research

Sample sizes are typically smaller in qualitative research because, as the study goes on, acquiring more data does not necessarily lead to more information. This is because one occurrence of a piece of data, or a code, is all that is necessary to ensure that it becomes part of the analysis framework. However, it remains true that sample sizes that are too small cannot adequately support claims of having achieved valid conclusions and sample sizes that are too large do not permit the deep, naturalistic, and inductive analysis that defines qualitative inquiry. Determining adequate sample size in qualitative research is ultimately a matter of judgment and experience in evaluating the quality of the information collected against the uses to which it will be applied and the particular research method and purposeful sampling strategy employed. If the sample size is found to be a limitation, it may reflect your judgement about the methodological technique chosen [e.g., single life history study versus focus group interviews] rather than the number of respondents used.

Huberman, A. Michael and Matthew B. Miles. Data Management and Analysis Methods. In Handbook of Qualitative Research. Norman K. Denzin and Yvonna S. Lincoln, eds. (Thousand Oaks, CA: Sage, 1994), pp. 428-444.

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Older Adults Do Not Benefit From Moderate Drinking, Large Study Finds

Virtually any amount increased the risk for cancer, and there were no heart benefits, the researchers reported.

By Roni Caryn Rabin

Even light drinking was associated with an increase in cancer deaths among older adults in Britain, researchers reported on Monday in a large study. But the risk was accentuated primarily in those who had existing health problems or who lived in low-income areas.

The study, which tracked 135,103 adults aged 60 and older for 12 years, also punctures the long-held belief that light or moderate alcohol consumption is good for the heart.

The researchers found no reduction in heart disease deaths among light or moderate drinkers, regardless of this health or socioeconomic status, when compared with occasional drinkers.

The study defined light drinking as a mean alcohol intake of up to 20 grams a day for men and up to 10 grams daily for women. (In the United States, a standard drink is 14 grams of alcohol .)

“We did not find evidence of a beneficial association between low drinking and mortality,” said Dr. Rosario Ortolá, an assistant professor of preventive medicine and public health at Universidad Autónoma de Madrid and the lead author of the paper, which was published in JAMA Network Open.

On the other hand, she added, alcohol probably raises the risk of cancer “from the first drop.”

The findings add to a mounting body of evidence that is shifting the paradigm in alcohol research. Scientists are turning to new methodologies to analyze the risks and benefits of alcohol consumption in an attempt to correct what some believe were serious flaws in earlier research, which appeared to show that there were benefits to drinking.

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• Published: 08 August 2024

Mendelian randomization study reveals causal effects of specific gut microbiota on the risk of interstitial cystitis/bladder pain syndrome (IC/BPS)

• Peng Jiang 1   na1 ,
• Cheng Li 1   na1 ,
• Zhiyong Su 1 ,
• Di Chen 1 ,
• Jinji Chen 1 &

Scientific Reports volume  14 , Article number:  18405 ( 2024 ) Cite this article

338 Accesses

Metrics details

• Bladder disease
• Chronic inflammation
• Diagnostic markers

Evidence from previous studies have demonstrated that gut microbiota are closely associated with occurrence of interstitial cystitis/bladder pain syndrome (IC/BPS), yet the causal link between the two is not well known. In this study, we performed a two-sample Mendelian randomization (MR) analysis to determine the possible causal association between gut microbiota with IC/BPS. Gut microbiota summary level data were derived from the genome-wide association study (GWAS) conducted by MiBioGen and the IC/BPS GWAS summary level data were obtained from the GWAS Catalog. Next, we performed an MR study to investigate the causal link between gut microbiota and IC/BPS. The primary method for causal analysis was the inverse variance weighted (IVW), and the MR results were validated through multiple sensitivity analyses. A positive association was found between IC/BPS and eight gut microbial taxa, including genus Bacteroides , genus Haemophilus , genus Veillonella , genus Coprococcus1 , genus Butyricimonas , family Bacteroidaceae , family Christensenellaceae , and order Lactobacillales. Sensitivity analysis revealed lack of significant pleiotropy or heterogeneity in the obtained results. This MR analysis reveals that a causal association exists between some gut microbiota with IC/BPS. This finding may is expected to guide future research and development of IC/BPS preventions and treatments based on the bladder-gut axis. However, given the clinical complexity and diagnostic challenges of IC/BPS, along with the limitations of using large-scale GWAS summary data for analysis, our MR results require further validation through additional research.

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Introduction.

Interstitial cystitis (IC), also known as bladder pain syndrome (BPS), manifests as chronic pelvic pain that is primarily associated with bladder (pain, pressure, discomfort) and is accompanied by persistent lower urinary tract symptoms lasting over six weeks, in the absence of an infection or specific etiological factors 1 . Currently, the etiology of IC/BPS is unknown, but the disease causes severe debilitation and affects the quality of life in affected individuals 2 . The incidence of IC/BPS has been arising, with an estimated rate ranging from approximately 0.01–2.3%. Moreover, females have a five times higher prevalence compared with that of males 3 . The precise etiology and pathogenesis of IC/BPS are not fully understood. Depending on the presence or absence of Hunner lesions, IC/BPS can be divided into Hunner-type interstitial cystitis (HIC) and BPS, which can be differentiated through cystoscopy 3 . However, diagnosing BPS remains highly challenging due to the significant variability in clinical presentations among individuals. Although several therapeutic approaches have been performed, the effectiveness of current treatments for IC/BPS is poor, with the recurrence rate reported to be high during long-term follow-up 4 . Some patients even require destructive surgery such as cystectomy 5 . Therefore, to alleviate the burden of IC/BPS, it is imperative to investigated the etiology and identify more effective therapeutic targets.

The pathophysiological mechanisms of IC/BPS are multifactorial, yet our understanding of them remains limited 6 . Implying intercommunication between the bladder and the gut, the conceptualization of the bladder-gut-brain axis suggests that gut functionality may influence functional urological disorders, including IC/BPS 7 . Gut microbiota have been reported to modulate gut functionality 8 , and dysbiosis leads to the occurrence of inflammatory, metabolic, mental, and immune-related diseases in humans 9 . Current studies have indicated that the composition of the human gut microbiota is influenced by various factors such as diet 10 , aging 11 , and antibiotic use 12 . Although the phenotype of the gut microbiota is shaped by postnatal environments, it has been reported that the host’s genetic state also affects the composition of gut microbiota 13 . Given the overlapping microbes in the diverse symptoms of gut and bladder diseases implies that the microbial community may modulate the communication between the bladder and the brain-gut axis 14 , 15 . Both the urine microbiota and the gut microbiota are essential components of the human microbiome, and some studies have suggested that the gut may be a potential origin of the urinary microbiota 15 . Numerous studies have demonstrated that dysbiosis of the urine microbiota is associated with various urinary diseases, including IC/BPS 16 . However, research on the relationship between the gut microbiota and IC/BPS remains relatively limited. In recent years, high-throughput sequencing has helped to uncover the relationship between gut microbiota and IC/BPS. Studies employing 16S rRNA sequencing methods have demonstrated dysbiosis in the gut microbiota of individuals with IC/BPS compared to controls 17 . This observation was further supported by an animal study, where administration of anaerobes cultured from the stool of IC/BPS patients exacerbated pelvic allodynia when orally gavaged to experimental mice 18 .

Although above studies have linked gut microbiota to IC/BPS, they are primarily observational in nature, often based on small sample sizes and are susceptible to confounding factors. Consequently, research has not been unable to uncover the specific causal connection between the two. Therefore, conducting a thorough genetic-level assessment of the causal association between gut microbiota and IC/BPS is imperative.

The Mendelian randomization (MR) method can elucidate the causal association between exposure and outcome by utilizing single nucleotide polymorphisms (SNPs) as instrumental variables (IVs) 19 . Because genetic variations are randomly allocated at conception, MR studies are less prone to the influence of reverse causation or confounding factors which is often observed in traditional observational methods 20 . In recent years, the hypothesis of a causal association between gut microbiota and various diseases has been assessed and confirmed by multiple MR studies 21 , 22 , 23 .

In this investigation, we obtained summarized GWAS data on gut microbiota and IC/BPS from publicly available extensive genome-wide association studies (GWAS). We utilized a two-sample MR approach to analyze these data, unveiling the causal effect of specific gut microbiota on the risk of IC/BPS. The aim of our study was to reveal a new biological marker for the diagnosis and treatment of patients with challenging IC/BPS, as well as to offer partial evidence for bladder-gut communication within the bladder-gut-brain axis.

Data sources

The complete design of this study is shown in Fig.  1 . Given the chronic nature of IC/BPS, GWAS data were derived using the diagnostic term “Interstitial cystitis (chronic)” in line with the ICD-10 classification. The GWAS data for (chronic) interstitial cystitis (ID: GCST90044234), involving 240 cases and 456,108 controls of European ancestry, were obtained from the GWAS Catalog ( https://www.ebi.ac.uk/gwas/) 24 . In the GWAS data we obtained, chronic interstitial cystitis is defined as “a condition with recurring discomfort or pain in the urinary bladder and the surrounding pelvic region without an identifiable disease. Severity of pain in interstitial cystitis varies greatly and often is accompanied by increased urination frequency and urgency”. This definition corresponds to the ICD-10 diagnosis code N30.1 [Interstitial cystitis (chronic)], and the GWAS data we used included patients meeting this diagnosis code. While there are some variations in the definitions of IC/BPS across different guidelines 2 , our comparison revealed that the ICD-10 classification’s definition of IC/BPS is largely consistent with those in these guidelines. Therefore, we believe that using the ICD-10 classification’s definition for diagnosing and selecting patients with IC/BPS is appropriate and reliable.

The overview of the study design and flowchart. GWAS genome-wide association study, MR Mendelian randomization, SNP single-nucleotide polymorphism, MR-PRESSO Mendelian Randomization Pleiotropy RESidual Sum and Outlier, IC/BPS interstitial cystitis/bladder pain syndrome.

The summary-level data related to gut microbiota ( https://mibiogen.gcc.rug.nl/ ) were derived from the extensive GWAS MiBioGen consortium. In this GWAS meta-analysis, 211 bacterial taxa units were analyzed, which included 9 phyla, 16 classes, 20 orders, 35 families, and 131 genera, with 18,340 participants from 24 cohorts across 11 countries 25 . To ensure accuracy, 196 taxa were retained after exclusion of 15 bacterial taxa with unknown family and genus in this study.

Selection of instrumental variables

The following criteria were used to select significant instrumental variables: (1) We set a threshold of p  < 1 × 10 −5 (locus-wide significance) to identify SNPs that were significantly associated with the exposure data instead of p  < 1 × 10 −8 (genome-wide significance) because the number of SNPs obtained using the latter threshold was limited 26 . (2) The “TwoSampleMR” package was used to obtain instrumental variables from independent genetic loci in the 1000 Genomes EUR data. The clumping distance was set at 10,000 kb, along with a linkage disequilibrium (LD) threshold of R 2  < 0.001. The SNPs with the most significant p -values linked to the 196 bacterial taxa were subjected to clumping. (3) To ensure the causal relationship outcome between gut microbiota and IC/BPS was not affected by alleles, palindromic SNPs were excluded during GWAS data harmonization. (4) The F -statistic was utilized to test the strength of instrumental variables to evaluate the impact of weak instrument bias on causal effect estimates. If the associated F -statistic exceeded 10, weak instrumental bias was deemed non-existent 27 .

Statistical analysis

To estimate the potential causality between gut microbiota and IC/BPS, several methods including random-effects inverse variance weighted (IVW), weighted median, and MR-Egger were employed. In the MR analysis, the IVW method was applied as the primary approach 28 . The IVW method, which includes the Wald estimator and Delta method, was used to initially calculate the ratio estimates for individual SNPs. Subsequently, these individual estimates were aggregated to obtain the primary causal estimate 29 . To obtain more robust estimates across various scenarios, MR-Egger and weighted median methods were utilized to enhance IVW esimates, although they yielded lower efficiency (resulting in wider confidence intervals) 30 .

To explore the existence of potential heterogeneity and pleiotropy in the MR results, we performed sensitivity analysis. Heterogeneity was assessed using Cochrane’s Q test, and it was considered present when the instrumental variable had a p -value < 0.05. Potential horizontal pleiotropy was explored by the MR-Egger regression method and was considered present if intercept’s p -value < 0.05 31 . Pleiotropy outliers were identified by the MR-PRESSO method, and causal effect estimates were obtained using the IVW method on the plausible SNPs 32 . In addition, to determine whether a single SNP was driving the MR estimates, we performed leave-one-out analysis 33 . All statistics were performed using The “TwoSampleMR” package (version 0.5.8) in R (version 4.3.2), which can be accessed at https://www.r-project.org/ .

Ethics declarations

Additional review or approval by an ethics committee was not needed for this study because the GWAS summary statistics data were already publicly available. All participating studies had obtained informed consent in accordance with protocols approved by their institute’s ethics committee.

Table 1 shows that identified 106 SNPs associated with IC/BPS from eight bacterial taxa using the IVW method after quality control. In addition, the IVW method revealed a positive relationship between these eight bacterial taxa and the risk of IC/BPS (Table 1 and Fig.  2 ): genus Bacteroides (OR = 4.273, 95% CI:1.361–13.413, p  = 0.013), genus Haemophilus (OR = 2.175, 95% CI:1.172–4.036, p  = 0.014), genus Veillonella (OR = 2.379, 95% CI:1.037–5.458, p  = 0.041), genus Coprococcus1 (OR = 2.704, 95% CI:1.118–6.542, p  = 0.027), genus Butyricimonas (OR = 2.265, 95% CI:1.151–4.455, p  = 0.018), family Bacteroidaceae (OR = 4.273, 95% CI:1.361–13.413, p  = 0.013), family Christensenellaceae (OR = 2.623, 95% CI:1.045–6.605, p  = 0.040), and order Lactobacillales (OR = 2.142, 95% CI:1.024–4.480, p  = 0.043). These findings suggest that these microbiota might increase the incidence of IC/BPS. Among the eight causal associations, the F-statistic was larger than 10 for all IVs, suggesting low risk of weak instrument bias in the estimates, as detailed in Table 1 .

Scatter plots illustrating the causal effect of gut microbiota on IC/BPS. ( A ) Genus Bacteroides ( B ) Genus Haemophilus ( C ) Genus Veillonella ( D ) Genus Coprococcus1 ( E ) Genus Butyricimonas ( F ) Family Bacteroidaceae ( G ) Family Christensenellaceae ( H ) Order Lactobacillales. Each black dot indicates a SNP, with the x-axis denoting the SNP effects on gut microbiota and the y-axis representing SNP effects on IC/BPS. The slope of the line corresponds to causality estimates calculated using three MR methods. SNP single-nucleotide polymorphism, MR Mendelian randomization, IC/BPS interstitial cystitis/bladder pain syndrome.

The sensitivity analysis did not reveal any significant heterogeneity or pleiotropy (Table 1 ). No significant heterogeneity was detected among these IVs based on the results of the Cochran’s Q test. Furthermore, the MR-Egger regression analysis results confirmed that there was no significant horizontal pleiotropy. In the MR-PRESSO analysis, no outliers were detected, further supporting the MR-Egger regression findings. Lastly, we confirmed that the MR estimates were not driven or biased by any single SNP because no outlier SNPs were identified by the Leave-one-out test (Fig.  3 ).

Leave-one-out plots for the causal effect of gut microbiota on IC/BPS. ( A ) Genus Bacteroides ( B ) Genus Haemophilus ( C ) Genus Veillonella ( D ) Genus Coprococcus1 ( E ) Genus Butyricimonas ( F ) Family Bacteroidaceae ( G ) Family Christensenellaceae ( H ) Order Lactobacillales. The line depicts the 95% confidence interval derived from the inverse variance weighted method.

To our knowledge, this study is the first extensive MR investigation into the causal effect of gut microbiota on IC/BPS. While the gut microbiota have been identified to be correlated with IC/BPS in previous research 17 , establishing a causal link has been challenging due to the potential impact of confounding factors. Our results, however, indicate that specific gut microbiota (1 order taxon, 2 family taxa, and 5 genus taxa) are causally associated with the risk of IC/BPS. This insight offers a new angle regarding the diagnosis and treatment of IC/BPS.

In the human body, the gut-brain axis has been documented 34 , with evidence suggesting that microbes are involved in this axis, known as the microbiota-gut-brain axis 35 . Previous research has indicated that the gut-brain axis and the microbiota-gut-brain axis contribute to various diseases 36 , 37 , 38 , 39 , 40 , and there is inflammatory signal transmission between the gut and the brain 41 . Given the frequent coexistence of functional urological disorders, including IC/BPS, with specific gastrointestinal dysfunctions (such as irritable bowel syndrome) and mental disorders (such as depression), we speculate that there are interactions among the bladder, intestines, and brain. Based on this, a hypothesis is proposed regarding the bladder-gut-brain axis in the human body 7 , 14 . The role of microbiota in mediating communication between the bladder and the gut-brain axis has been postulated based on their essential functions in the gut-brain axis. Clinical studies have identified correlations between gut microbiota alterations and the occurrence of functional urological disorders, such as IC/BPS, chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), and overactive bladder (OAB) 17 , 42 , 43 . However, causation remains unproven. In this study, we demonstrate that gut microbiota have a causal effect on IC/BPS, providing new perspectives regarding the potential interactions between the bladder and gut. Moreover, we provide a partial preliminary evidence for further investigation into the bladder-gut-brain axis.

Our study identified causal associations between eight gut microbiota and IC/BPS. These microbiota taxa were all positively correlated with the risk of IC/BPS. However, due to the limited research on this relationship, no studies have reported changes in these microbiota taxa in patients with IC/BPS. While the clinical observational study mentioned earlier reported statistically significant decreases in the abundance of specific microbiota in fecal specimens from IC/BPS patients, trends of increased abundance were also observed in some gut microbiota, although not statistically significant 17 . However, observational studies are often affected by numerous confounding factors, especially given that IC/BPS treatments involve dietary management and antimicrobial drug use 3 . This complexity makes it difficult to interpret the findings obtained in studies on gut microbiota in IC/BPS patients. Therefore, we believe our MR study, less susceptible to confounding factors, provides a valuable foundation for further research.

In this research, we found that genus Bacteroides and family Bacteroidaceae were both causally related to IC/BPS, with positive results observed in both the IVW and weighted median analyses for genus Bacteroides . Moreover, the genus Bacteroides , belonging to the family Bacteroidaceae , is one of the most prevalent species in the human gut microbiota, involved in many biological processes. This species can be transmitted from mother to child during vaginal delivery, becoming part of the human microbiota in the earliest stages of life 44 . Bacteroides are typically probiotics in the gut, with the potential to become opportunistic pathogens when they translocate from the gut to other parts of the body, contributing to or exacerbating infections. This translocation may be triggered by factors such as compromised immune systems, intestinal barrier disruption, surgical injury, excessive antibiotic use, and aging 45 . Current research suggests that one potential origin of the urinary microbiota may be the gut 15 . Additionally, other studies have indicated a correlation between dysbiosis of the urinary microbiota and IC/BPS 16 . Therefore, it is worth investigating whether the translocation of Bacteroides from the gut could be one of the reasons for the positive correlation between Bacteroides and the risk of IC/BPS.

Genus Haemophilus is a common pathogen that can colonize the oral, respiratory, and digestive tracts of humans, causing various infectious diseases. While urinary and genital infections caused by Haemophilus are relatively less common in humans compared to other sites, there are some reports of potential occurrence 46 , 47 , 48 , 49 . Genus Veillonella is an opportunistic pathogen found in the human respiratory, digestive, and urogenital tracts, with the potential to cause urinary and genital infections 50 . Our MR results indicated a positive correlation between the increased abundance of genera Haemophilus and Veillonella in the gut and the risk of IC/BPS. However, the underlying mechanisms remain unclear, and additional studies are necessary to validate this finding.

Genus Coprococcus1 and genus Butyricimonas are major producers of butyrate, which is considered beneficial for the gut, with anti-inflammatory properties and capacity to improve intestinal barrier function and mucosal immunity 51 . Family Christensenellaceae is considered to be one of the most heritable taxonomic groups 13 . Although research has demonstrated that the abundance of family Christensenellaceae is increased in patients with childhood asthma 52 , it is generally considered a probiotic, and its abundance is negatively correlated with inflammation 53 . However, contrary to previous research findings, this MR study suggests that the higher abundance of family Christensenellaceae, genera Coprococcus1 and Butyricimonas in the gut may elevate the risk of IC/BPS. Further research is advocated to validate our findings.

In this study, we found that Lactobacillales was the only microbial group on the order level that was causally associated with IC/BPS. Typically, the order Lactobacillales have several benefits to the human body. However, our results indicated that a higher abundance of the order Lactobacillales in the gut may contribute to the risk of IC/BPS. Although there is no research on the connection between gut Lactobacillales and IC/BPS, in a study on CP/CPPS, another functional urological disorder, researchers found that the gut Lactobacillales abundance was significant increased in mice with experimental autoimmune prostatitis (EAP) 54 . The potential biological mechanisms linking the two need to be further investigated.

This MR study offers several important findings. Firstly, it is the first two-sample MR analysis to investigate the potential causal relationship between gut microbiota and IC/BPS. Traditional observational studies are susceptible to bias due to factors such as reverse causality and confounding variables. Our approach introduces a novel method for screening candidate gut microbiota, thereby offering a valuable tool for identifying new biomarkers. Secondly, compared to small-scale randomized controlled trials, the summary-level genetic data from large-scale GWAS are derived from larger population samples, enhancing the study’s credibility. Lastly, our study conducted sensitivity analysis, which confirmed the absence of heterogeneity or pleiotropy, underscoring the statistical robustness of our findings.

However, this study has some limitations. Firstly, during the selection of instrumental variables based on the threshold of p  < 1 × 10 −8 (genome-wide significance), few SNPs were obtained, which restricted further analysis. Therefore, we selected a more lenient threshold of p  < 1 × 10 −5 (locus-wide significance) to obtain for SNPs, which may potentially influence the results. Secondly, we analyzed gut microbiota only at the taxonomic level of the genus and above, which may not have included more specific levels such as species or strains. Employing advanced metagenomic sequencing would enhance specificity and accuracy in gut microbiota GWAS outcomes. Thirdly, the large-scale GWAS summary data used in MR studies may be influenced by selection bias, sociodemographic factors, cultural differences, and other factors during the statistical process. This impact may be particularly pronounced given the inherent clinical complexity and diagnostic challenges of IC/BPS. Fourthly, the use of GWAS summary statistics of IC/BPS patients rather than raw data in the study resulted in the inability to perform subgroup analysis. In addition, obtaining more detailed IC/BPS patient inclusion/exclusion criteria or other individual patient information from GWAS summary statistics was difficult. Fifthly, since the study cohort primarily consisted of individuals of European ancestry, any extrapolation of our findings to other ethnic groups should be conducted with caution. Sixthly, although the instrumental variables chosen for the analysis were closely linked to gut microbiota taxa and met the core MR assumptions, we cannot rule out the potential of weak instrument bias. Finally, during the collection of gut microbiota samples, the microbial abundance may vary depending on the participants diet, medication, and other factors.

Conclusions

In summary, we employed a two-sample MR analysis with publicly available summary-level data from GWAS to explore the causal relationship between gut microbiota and IC/BPS. Through this approach, we identified potential pathogenic flora associated with the development of IC/BPS. While extrapolating the MR result to guide clinical intervention might be inappropriate at this stage, these microbial communities may serve as innovative biomarkers in IC/BPS-related research, offering new opportunities for the treatment and prevention of IC/BPS. This study also offers partial preliminary evidence for future investigations into the bladder-gut communication and its potential implications in clinical practice.

However, our study has several limitations. Similar to other MR studies, the large-scale GWAS summary data we used may be influenced by selection bias, sociodemographic factors, cultural differences, and other factors during the statistical process. Additionally, GWAS summary data, unlike raw data, do not provide more detailed information such as individual patient subtypes or specific inclusion/exclusion criteria. Given the clinical complexity and diagnostic challenges of IC/BPS, these limitations suggest that our MR results require further validation through additional research. In the future, we will conduct animal experiments or large and prospective cohort studies to validate our findings and explore the associated mechanisms.

Data availability

All the statistics can be found in GWAS Catalog ( https://www.ebi.ac.uk/gwas/ ) and GWAS MiBioGen consortium ( https://mibiogen.gcc.rug.nl/ ). Further inquiries can be directed to the corresponding author.

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Acknowledgements

We would like to express our gratitude to the participants and investigators involved in the GWAS utilized in the present study.

This study was supported by the National Natural Science Foundation of China (Grant no: 81860142) .

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These authors contributed equally: Peng Jiang and Cheng Li.

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Department of Urology, The First Affiliated Hospital of Guangxi Medical University, Nanning, 530001, Guangxi, China

Peng Jiang, Cheng Li, Zhiyong Su, Di Chen, Hua Li, Jinji Chen & Hua Mi

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P.J. contributed to the writing of the manuscript and the visualization. C.L., Z.S., and H.L. contributed to data collection and analysis. D.C. and J.C. supervised the study. H.M. and C.L. contributed to the study design and manuscript revision. All authors contributed to the article and approved the submitted version.

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Jiang, P., Li, C., Su, Z. et al. Mendelian randomization study reveals causal effects of specific gut microbiota on the risk of interstitial cystitis/bladder pain syndrome (IC/BPS). Sci Rep 14 , 18405 (2024). https://doi.org/10.1038/s41598-024-69543-9

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DOI : https://doi.org/10.1038/s41598-024-69543-9

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