A research gap is a question that existing research has not answered, has answered unconvincingly, or has answered only for other people and places. If you are planning a PhD, finding one comes before everything else: it decides your research question, your proposal, and how convincing your application looks to a supervisor or scholarship panel.
This guide covers the four quick routes to a gap, the seven types of gap researchers recognise, a step-by-step method with a literature matrix, and how to test a gap before you commit to it. Reviewed against Miles (2017) and Robinson et al. (2011).
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What a Research Gap Is, and What It Isn’t
A PhD asks you to make an original contribution to a narrow field. That is why you work on a small, specific area and not a whole discipline. A research gap is what makes that contribution possible: the place where current knowledge stops.
“Nobody has studied this” is not enough. Nobody may have studied it because it doesn’t matter, or because the data can’t be collected. A useful gap is a real absence in the literature that is also worth filling and possible to fill.
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The Seven Types of Research Gaps
Miles (2017) groups research gaps into seven types, building on earlier frameworks. Knowing the type helps you search for it.
| GAP TYPE | WHAT IT MEANS | WHAT TO LOOK FOR |
|---|---|---|
| Evidence gap | Studies reach conflicting conclusions | Papers on the same question that disagree |
| Knowledge gap | A topic or question has not been studied enough | Little or no work on a specific question |
| Population gap | The group, region or context studied is narrow | Findings drawn mostly from Europe or other developed economies, with Africa missing |
| Methodological gap | One method dominates, and another could show more | Nearly all quantitative studies, with no mixed-methods work |
| Empirical gap | An idea or model has not been tested with data | A framework proposed in theory but never tested |
| Theoretical gap | Existing theory doesn’t explain the findings, or has not been applied | Results that no current model accounts for |
| Practical-knowledge gap | What practitioners do differs from what research says | Studies advise one approach while professionals use another |
Robinson et al. (2011) offer a second lens, developed for health research. They describe four reasons evidence can fall short:
- insufficient or imprecise information,
- biased information,
- inconsistent or unknown consistency,
- and not the right information.
They also suggest describing a gap using population, intervention, comparison, outcomes and setting. In plain terms, ask who was studied, what was done, compared with what, measured how, and where.
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How to Identify a Research Gap, Step by Step
- Start broad, then narrow. Pick an area you can sustain for several years, then keep narrowing to a specific problem.
- Read recent literature. Focus on journal articles, conference papers and recent studies, typically from the last five years or so, plus the foundational papers in your area. Start with recent review articles, because they summarise what is known and often state what is missing. Search Google Scholar, Scopus, Web of Science and Semantic Scholar, and try citation-mapping tools to see how papers connect.
- Read the limitations and future research sections. Authors often state exactly what they could not do and what should be studied next. These sections can point you straight to a gap.
- Look for inconsistencies and unanswered questions. Compare studies that disagree. Notice which populations, regions and contexts the literature covers. Check whether findings from European countries are being generalised to Africa, and whether every study uses the same kind of method.
- Check new technologies and trends. Look for developments that existing research has not examined in depth.
- Build a literature matrix. Make a spreadsheet with one row per paper. Use these columns: author and year, country or context, population, method, main findings, limitations, and future research suggested. After 20 to 30 rows, patterns appear. You may see the same missing group, the same unused method, or the same limitation repeated.
- Test the gap. Search again using different keyword combinations. Check the most recent two or three years. Look at which papers cite the key studies in your area. Then discuss your gap with a potential supervisor, because they can tell you whether it is real.
- Judge whether it is worth filling. Ask whether it matters for theory, practice or policy, and whether you can complete it with the time, data, access and funding you have.
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A Hypothetical Example
Suppose you review recent studies on digital learning tools in secondary schools. In your matrix you notice that nearly every study surveys students in high-income countries, measures test scores only, and lists teacher perspectives as something it could not examine. Your gap statement could read:
“Existing research on digital learning tools has examined student outcomes in high-income settings. However, little is known about how teachers in Nigerian secondary schools adopt these tools and why. This study addresses that gap through a mixed-methods study of teachers in [state], contributing evidence for policy on teacher training.”
A general formula for any gap statement: Existing research on [topic] has established [what is known]. However, [what is missing: a contradiction, a context, a method, a theory]. This study addresses that by [approach] in [context], contributing [to theory or practice].
Where the Gap Shows Up in a PhD Proposal or Scholarship Application
The gap appears in your introduction and problem statement, at the end of your literature review, and in the justification for your research questions. Scholarship panels read for it. Many scholarship providers score applications against published selection or scoring criteria, and those criteria often reward a clearly stated research problem, a clear proposed study and a realistic plan to complete it. Check the scholarship call for these criteria, or ask the scholarship provider directly, and prepare your application against them. Proposals for programmes like DAAD research grants also require a research proposal or study plan, which has to state what your work adds.
Common Mistakes
- Claiming “no one has studied this” without a systematic search. Check before you write it.
- Choosing a gap that is too broad or too narrow. Too broad cannot be completed, and too narrow may not matter.
- Treating “not studied in Africa” as enough. Explain why the African context would change the answer. Otherwise, it is only a change of location.
- Relying on old literature. An old gap may already be filled.
- Copying a gap from a review article. Confirm it still exists in newer papers.
- Trusting AI tools to find the gap for you. AI can overstate a gap or invent citations. Verify every paper it names.
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References
- Robinson KA, Saldanha IJ, Mckoy NA. Development of a framework to identify research gaps from systematic reviews. Journal of Clinical Epidemiology, 2011;64(12):1325-30. Framework summary on NCBI Bookshelf
- Miles DA. A Taxonomy of Research Gaps: Identifying and Defining the Seven Research Gaps. Doctoral Student Workshop: Finding Research Gaps, Research Methods and Strategies, 2017.
Frequently Asked Questions
What is a research gap in simple terms?
It is a question that existing studies have not answered well enough, either because it was never studied, the results conflict, or the evidence covers different people or places from yours.
How many papers do I need to read before I find a gap?
There is no fixed number. A practical sign is saturation: the same limitations, the same authors and the same citations keep reappearing as you read.
Is “not studied in Africa” enough for a PhD research gap?
Usually not on its own. Explain why the African context could change the findings, for example different institutions, infrastructure or populations, and what your study adds to theory or practice.
Where can I find future research suggestions?
Check the discussion and conclusion sections of recent papers, and read recent review articles. They often list what remains unanswered.
Does a research gap have to be big?
No. A PhD contributes original knowledge to a narrow area, so a precise gap you can complete is better than a broad one you cannot.
Can I rely on AI to identify a gap?
Use it to organise your reading if you wish, but check every claim and citation yourself, and confirm the gap with your own search and your supervisor.
Disclaimer: This guide reflects general academic practice and published frameworks on identifying research gaps. It does not replace advice from your supervisor or your target university. Requirements for research proposals vary by institution and scholarship, so always check the guidance for each programme you apply to.
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