Being open about what you could not do in your research is actually extremely positive, and it’s viewed favorably by editors and peer reviewers. Writing about your limitations without reducing your impact is a valuable skills that will help your reputation as a researcher.
Areas you might have “failed,” in other words, your limitations, include:
- Aims and objectives (they were a bit too ambitious)
- Study design (not quite right)
- Supporting literature (you’re in uncharted territory)
- Sampling method (if only you’d snowballed it)
- Size of your study population (not enough power)
- Data collection method (bias found its way in)
- Confounding factors (didn’t see that coming!)
Your limitations don’t harm your work and reputation. Quite the opposite, they validate your work and increase your contribution to your field.
Limitations are quite easy to write about in a useful way that won’t reducing your impact. In fact, it’ll increase it.
Why are limitations so important?
Regrettably, the publish-or-perish mentality has created pressure to only come up with successful results. It’s also not too much to say that journals prefer positive studies – where the findings support the hypothesis.
But success alone is not science. Science is trial and error.
So it’s important to present a well-balanced, comprehensive description of your research. That includes your limitations. Accurately reporting your limitations will:
- Help prevent research waste on repeated failures
- Lead to creation of new hypotheses
- Provide useful information for systematic reviews
- Further demonstrate the robustness of your study
Adding clear discussion of any negative results and/or outcomes as well as your study limitations makes you much better able to provide your readers (including peer reviewers) with:
- Information about your positive results
- Explanation of why your results are credible
- Ideas for future hypothesis generation
- Understanding of why your study has impact
These are good things. There’s even a journal for failure! That’s how important it is in science.
Some authors find it hard to write about their study limitations, seeing it as an admission of failure. You can do it, and you don’t have to overdo it, either.
Know your limitations and you can anticipate and record them
Before you even start your study or collect your data, you’re often aware of certain limitations on what you want to test or what results you’ll get. These are three broad areas of limitations. But there are certainly more. We admit our own limitations here. 😉
Study design limitations
These might include the procedures, experiments, or reagents (or funding) you have available. As well as specific constraints on the study population. There may be ethical guidelines, and institutional or national policies, that limit what you can do.
These are very common limitations to medical research, for example. We refer to these kinds as study design limitations. Clinical trials, for instance, may have a restriction on interventions expected to have a positive effect. Or there may be restrictions on data collection based on the study population.
Even if your study has a strong design and statistical foundation there might be a strong regional, national, or species-based focus. Or your work could be very population- or experimental-specific.
Your entire field of study, in fact, may only be conducive to incremental findings (e.g., particle physics or molecular biology).
These are inherent limits on impact in that they’re so specific. This limits the extendibility of the findings. It doesn’t however, limit the impact on a specific area or your field. Note the impact and push forward!
Statistical or data limitations
Perhaps the most common kind of limitation is statistical or data-based. This category is extremely common in experimental (e.g., chemistry) or field-based (e.g., ecology, population biology, qualitative clinical research) studies.
In many situations, testing hypotheses, you simply may not be able to collect as much data or as good quality data as you want to. Perhaps enrollment was more difficult than expected, under-powering your results.
Statistical limitations can also stem from study design, producing more serious issues in terms of interpreting findings. Seeking expert review from a statistician, such as by using Edanz scientific solutions, may be a good idea before starting your study design.
The above three are often interconnected. And they’re certainly not comprehensive.
As mentioned up top, you may also be limited by the literature. By external confounders. By things you didn’t even see coming (like how long it took you to find 10 qualified respondents for a qualitative study).
How to describe your limitations
Once you’ve identified possible limitations in your work, you need to get to the real point of this post – describing them in your manuscript.
Use the perspective of limitations = contribution and impact to maximize your chances of acceptance.
Reviewers, editors, and readers expect you to present your work authoritatively. You’re the expert in the field, after all. This may make them critical. Embrace that. Counter their possibly negative interpretation by explaining each limitation, showing why the results are still important and useful.
Where to write your limitations
Limitations are usually listed at the end of your Discussion section, though they can also be added throughout. Especially for a long manuscript or for an essay or dissertation, the latter may be useful for the reader.
Writing on your limitations: Words and structure
- This study did have some limitations.
- Three notable limitations affected this study.
- While this study successfully x, there were some limitations.
Giving a specific number is useful for the reader and can guide your writing. But if it’s a longer list, no need to number them. For a short list, you can write them as:
But this gets tiring for more than three limitations (bad RX: reader experience).
So, for longer lists, add a bit of variety in the language to engage the reader. Like this:
- The first issue was…
- Another limitation was…
An expert editor will be happy to help you make the English more natural and readable.
Structure for writing about a limitation
After your lead-in sentence, follow a pattern of writing on your findings and related limitation(s), giving a quick interpretation, back it with support (if needed), and offer the next steps.
This provides a complete package for the reader: what happened, what it means, why this is the case, and what is now needed.
In that way, you’ve admitted what may be lacking, but you’ve further established your authority. You’ve also provided a quick roadmap for your reader. That’s an impactful contribution!
Writing up a broader limitation
It might not always be logical or readable to give that much detail. As long as you fully describe and justify the limitation, you’ve done your job well.
Your study looked at a weight intervention over 6 months at primary healthcare clinics in Japan. The results were generally. But because you only looked at Japanese patients, these findings may not be extendible to patients of other cultures/nationalities, etc.
That’s not a failure at all. It’s a success. But it is a limitation. And other researchers can learn from it and build on it. Write it up in the limitations.
Finding: We found that, in the intervention group, BMI was reduced over 6 months.
Interpretation (and support): This suggests a regimen of routine testing and measurement followed by personalized health guidance from primary physicians had a positive effect on patients’ conditions.
Support: Yamazaki (2019) and Endo et al. (2020) found similar results in urban Japanese clinics and hospitals, respectively.
Limitation and how to use it: While these are useful findings, they are limited by only including Japanese populations. This does not ensure these interventions would be as effective in other nations or cultures. Similar interventions, adapted to the local healthcare and cultural conditions, would help to further clarify the methods.
Now you’ve stated the value of your finding, the limitation, and what to do with it. Nice impact!
Dealing with breakthroughs and niche-type limitations
Another hurdle you may hit is when your results are particularly novel or you’re publishing in a little-researched field. Those are limitations that need to be stated. In this case, you can support your findings by reinforcing the novelty of your results.
When breaking new ground, there are probably still many gaps in the knowledge base that need to be filled. A good follow-up statement for this type of limitation is to describe what, based on these results, the next steps would be to build a stronger overall evidence base.
Dealing with critical flaws
It’s possible that your study will have a fairly “critical” flaw (usually in the study design) that decreases confidence in your findings.
Other experts will likely notice this (in peer review or perhaps on a preprint server, they should notice it), so it’s best to explain why this error or flaw occurred.
You can still explain why the study is worth repeating or how you plan to retest the phenomenon. But you may need to temper your publication goals if you still plan to publish your work.
Curb your enthusiasm: Manage expectations
No one expects science to be perfect the first time and while your peers can be highly critical, no one’s work is beyond limitations. This is important to keep in mind.
Edanz experts can help by giving you an Expert Scientific Review and seeking out your limitations.
Our knowledge base is built on uncovering each piece of the puzzle, one at a time, and limitations show us where new efforts need to be made. Much like peer review, don’t think of limitations as being inherently bad, but more as an opportunity for a new challenge.
All research faces problems: Being honest impresses people much more than ignoring your limitations.