Your manuscript’s limitations paragraph: Can you be too honest?

Nobody enjoys discussing their flaws, but we all have them, your study included. When you design a study, you will have to make choices that inevitably weaken your ability to definitively answer your research question. These choices are usually because of limited resources: time, money, access to the population of interest, etc. For example, you don’t have 25 years to follow a cohort of people; you didn’t have grant funding to run the fancy analysis, so you used something less expensive; it’s really difficult to recruit the people you are interested in. Reviewers and readers expect you to acknowledge some of your study’s limitations, but you don’t need to list them all.

Here is an example of a poorly written limitations paragraph: “This study suffers from several limitations. The small sample size, and the fact the participants were mostly students, likely biases the results. In addition, the study was cross-sectional, which is a limitation. Future research should address these limitations.” The writing is vague – how were the results biased? How do the limitations matter – is the sample too small to adequately test the research question?

An effective way to approach your limitations paragraph is to identify some of the more important weaknesses and, if possible, explain how you addressed the weakness or why you don’t think the limitation made much of a difference in outcomes. Here are two examples of how to address specific limitations:

“Subjective measures of sleep quality were used, which can suffer from social desirability bias; however, the surveys have been validated in our study population, while the cross-over design minimizes bias. Confirmation with objective measures is needed to corroborate subjective findings.” Here we explain what kind of bias might be present but also indicate that our design likely mitigated that effect somewhat. We also suggest how the study design could be improved in the future.

 “The ability to generalize results to other racial groups is limited, as there were only 22 Black participants; however, post hoc testing confirmed the sample size was sufficient for the statistical analysis conducted.” The limitation was noted, but the author explains why or how the effect is likely minimal.

Here is a stronger limitations paragraph: “There are important limitations that affect the interpretation of these findings. First, the sample consisted primarily of undergraduate students from a single Midwestern university, which may limit the generalizability of the outcomes to other age groups or institutions. Second, the cross-sectional design does not allow for causal determination. Third, all measures relied on self-reported data, which may have introduced response biases such as social desirability. Despite these limitations, this study provides evidence for associations between financial stress and diet quality within this population. Employing longitudinal designs and more diverse samples will be able to confirm the observed relationships.”

Present your limitations as boundaries rather than mistakes. Your limitations help to put your findings in context. There is no perfect study! If you need help with writing your limitations section – or any other part of your manuscript – reach out at www.absolutelyenglish.com.