How to Write a Literature Review for a PhD or Grant ProposalWith structure templates, a synthesis matrix, database guide, and a 24-item interactive checklist

What is a literature review — and what it is not

A literature review is a critical, synthesised account of existing knowledge on your research topic. It shows what is known, how it is known, where scholars disagree, and — most importantly — where a genuine gap exists that your research will address.

What it is not: a reading list, an annotated bibliography, a chronological history of the field, or a series of summaries. The most common failure mode is a review that reads as a sequence of paragraphs beginning "Smith (2020) found that… Jones (2021) argued that… Chen (2022) showed that…" — each paper treated as a separate item rather than a thread in a larger argument. That is description, not review.

The synthesised version does what a literature review must do: it connects sources, identifies a pattern, and points toward a specific explanatory problem worth investigating.

The four types of literature review — and which one you need

Not all literature reviews are the same. The type you write depends on your purpose: is this for a PhD thesis chapter, a standalone journal article, a grant proposal, or a systematic review publication? Getting this wrong wastes weeks of work.

Before you write: searching and organising your sources

The quality of your literature review is capped by the quality of your search. Researchers who start writing too early, before they have read widely enough, end up missing key papers — and supervisors and reviewers notice. A structured search phase takes time upfront but saves it later.

Define your scope before searching

Scope means knowing what you are and are not looking for before you open any database. At minimum, define: your disciplinary boundaries (are you searching only within your field or across related disciplines?), your date range (typically the last 10–15 years, with older sources for seminal works), your geographic focus (is the review global or region-specific?), and your language (most academic databases will return English-language results by default — decide whether you need to expand this).

Build a keyword list with Boolean logic

Search engines and academic databases respond to Boolean operators: AND, OR, NOT. Build a keyword table before you search. For each core concept in your research question, list synonyms and related terms in a column — then combine columns with AND and items within a column with OR.

Screen systematically

After your initial search returns results, screen in two passes: first by title and abstract (can you rule it out based on these alone?), then by full text for the papers that pass the first screen. Keep a simple log of how many papers were returned, how many passed each screen, and why papers were excluded. For a PhD proposal, this log demonstrates methodological rigour. For a systematic review, it is mandatory.

Best academic databases — by field and access type

Not all databases index the same journals. Using only Google Scholar is a common mistake — it has broad coverage but inconsistent indexing and no advanced filtering. Use field-appropriate databases as your primary source and Google Scholar as a supplement.

How to structure a literature review

The most effective structure for a thematic literature review follows three moves: establish the field, identify the debate, locate the gap. Every paragraph, every section, should serve one of these three purposes.

Move 1 — Establish what is known (broad → narrow)

Open by situating your topic within its broader context. What do we know about the general phenomenon? What is the established consensus in the field? This section surveys the landscape and orients your reader. It should not be exhaustive — select the most significant and cited works, not every paper ever written on the subject.

Move 2 — Identify debates, tensions, and contradictions

Real fields have arguments in them. Where do scholars disagree? Where do studies reach conflicting conclusions, and why? Showing that you understand the debates in your field — and can explain the methodological or theoretical reasons behind disagreements — is what distinguishes a sophisticated review from a surface-level survey.

Move 3 — Locate the gap and justify your research

This is the most important move in the review, and the one most PhD students underwrite. The gap you identify must be specific, evidenced, and clearly connected to your research questions. It is not enough to say "this has not been studied" — you must explain why the absence matters, who is affected by it, and how your research will address it.

The strong version is specific about what exists, specific about what does not, and identifies the exact variable and context that your research will address. A reviewer reading this knows exactly what gap is being filled and why it matters.

The synthesis matrix — your most useful organising tool

Before you write a single sentence of your review, build a synthesis matrix. This is a table where each row is a source and each column is a theme, concept, or variable relevant to your research question. Filling it out forces you to read actively rather than passively, and the patterns that emerge — which themes are well-covered, which are absent — directly reveal your research gap.

Once the matrix is complete, your literature review structure almost writes itself: each column with significant coverage becomes a thematic section; cells that are mostly empty point toward your gap; papers that appear across multiple columns are your most important sources and should be cited and discussed in depth.

Identifying a genuine research gap

Not every unexplored area is a research gap worth filling. The question is not just "has this been studied?" but "does it matter that it has not been studied?" A gap is only worth pursuing if it has consequences — for theory, for practice, for policy, or for the communities affected by the phenomenon you are studying.

Types of gaps to look for

• Contextual gap: A phenomenon is well-studied elsewhere but not in your specific context (e.g. well-studied in the US but not in Nigeria or sub-Saharan Africa)
• Population gap: Existing research covers one group but not another (e.g. studied in adult learners but not in undergraduate students)
• Methodological gap: Existing studies all use one method and a different approach would yield new insights (e.g. all quantitative; no qualitative understanding of lived experience)
• Temporal gap: The literature predates a significant change in the field (e.g. pre-COVID studies on remote learning are now less applicable)
• Theoretical gap: Existing work applies one theoretical framework and another lens would illuminate overlooked dimensions
• Variable gap: A key variable has been studied in isolation but never in combination with another relevant factor

8 literature review mistakes that weaken PhD proposals and grant applications

1. Summarising instead of synthesising. The single most common error. Each paragraph should make a point about what the literature collectively shows — not describe what individual papers found. If your paragraphs start with author names rather than arguments, you are summarising.
2. Not stating the gap explicitly. Many researchers imply their gap without stating it directly. Reviewers should not have to infer it. Write a sentence that says precisely what is missing from the literature and why your research fills that exact space.
3. Over-relying on secondary sources. Citing a textbook that cites the original study, rather than reading the original study yourself, is a risk. The textbook may have misrepresented the finding. Read primary sources for anything central to your argument.
4. Using outdated literature as current evidence. A 2009 study can be cited as a foundational or historical reference, but should not be presented as current evidence of what is known. Fields move quickly; a review that relies heavily on decade-old sources signals you have not engaged with recent developments.
5. Only citing literature that supports your view. A strong review acknowledges contradictory findings and explains them. Ignoring studies that complicate your argument makes the review look selective and weakens your credibility as a researcher.
6. Searching only one database. No single database covers everything. A review based only on Google Scholar will miss discipline-specific journals, African-published research (use AJOL), and grey literature. Use at least three sources.
7. No clear connection to your research questions. The literature review must lead somewhere. If a reader finishes it without understanding why your specific research questions are the logical next step, the review has not done its job. The gap you identify should directly motivate your objectives.
8. Inconsistent citation formatting. Mixing APA and Chicago, inconsistent author formatting, or missing page numbers for direct quotes are all signals of carelessness. Use a reference manager (Zotero is free) to enforce consistency automatically.

Full literature review checklist (interactive)

Work through this checklist as you plan, search, and write. Tick each item as you complete it.

Frequently asked questions