To write a literature review, search systematically for relevant research, evaluate it, group it by theme and write a synthesis that shows what is known, where studies disagree and what gap remains.
A literature review is an argument about the state of knowledge, not a list of summaries. It may be a standalone assignment or a chapter in a dissertation, thesis or research paper. This page covers types of review, searching, evaluating, structuring, synthesis, finding the gap and a checklist.
The Six Steps of a Literature Review
- Define a focused question and scope.
- Search databases systematically and record your search terms.
- Screen and evaluate sources for relevance and quality.
- Group findings into themes or debates.
- Write each theme as a synthesis, comparing and evaluating studies.
- Conclude with the gap your research or question addresses.
What a Literature Review Is and Is Not
A literature review critically discusses published research on a topic. It shows the main findings, the methods used, where studies agree and disagree, and what is still unknown.
It is not an annotated bibliography, which treats sources one by one. It is not a summary of everything ever written on the topic. And it is not a place for your own new data; that belongs in your results.
Types of Literature Review
| Type | What it does | Where you meet it |
|---|---|---|
| Narrative (traditional) | Discusses key research thematically, selected by the author | Essays, dissertation chapters |
| Systematic | Uses a predefined protocol to find and appraise all relevant studies | Health sciences, postgraduate research |
| Scoping | Maps the extent and type of research in a field | New or broad topics |
| Integrative | Combines different study designs to build a fuller picture | Nursing and social sciences |
Most undergraduate and taught master's reviews are narrative, but many still expect a transparent search strategy. Check your brief.
Searching and Selecting Sources
A good search is planned. Break your question into key concepts and list synonyms for each.
- Databases: use subject databases such as PubMed or CINAHL for health, PsycINFO for psychology, and Scopus or Web of Science for wider searches.
- Boolean operators: combine terms with AND, OR and NOT, for example ("remote work" OR telework) AND productivity.
- Limits: set date ranges, languages and publication types that fit your scope.
- Citation chasing: check the reference lists of key articles and see who has cited them since.
- A search log: record databases, terms, dates and results so you can describe your method.
Evaluating Sources
For each study, ask who wrote it, where it was published, how it was designed, how large the sample was and whether the conclusions follow from the data. Peer review is a starting point, not a guarantee of quality.
Organize by Theme, Not by Source
The single biggest improvement most reviews need is to stop discussing one source per paragraph. Instead, group studies by theme, debate, method or chronology.
A simple way to find themes is a synthesis matrix: a table with sources as rows and key questions as columns.
| Source | Setting | Method | Effect on productivity | Explanation offered |
|---|---|---|---|---|
| Study A | Call center | Field experiment | Increase | Fewer interruptions |
| Study B | Tech firm | Survey | Mixed | Collaboration costs |
| Study C | Public sector | Interviews | Decrease for new staff | Less informal learning |
Reading down the columns reveals patterns: here, effects seem to depend on task type and staff experience. Those patterns become your themes. The studies in the table are illustrative.
Structure of a Literature Review
| Section | What it does |
|---|---|
| Introduction | Defines the topic and scope, explains why it matters and how the review is organized |
| Method (if required) | Databases, search terms, inclusion and exclusion criteria |
| Thematic sections | Each theme synthesizes and evaluates the relevant studies |
| Gap and conclusion | Summarizes what is known, what is contested and what is missing |
Writing Synthesis Instead of Summary
Synthesis means discussing several studies together: showing where they agree, where they differ and why. Compare these two versions.
Summary: Study A found that remote work increased productivity. Study B surveyed tech workers and found mixed results. Study C interviewed public sector staff and found productivity fell for new employees.
Synthesis: Evidence on remote work and productivity is mixed, and the differences appear to depend on the type of work and the employee's experience. Gains are clearest in routine, individual tasks such as call handling (Study A), while collaborative and learning-intensive roles show weaker or negative effects (Studies B and C). Because Study B relied on self-report, its findings may also reflect perceptions rather than measured output.
The synthesis makes a claim, groups studies to support it and evaluates a method. That is what "critical" means in a literature review.
Identifying the Gap
The gap is what the existing research has not yet answered. It might be a population not studied, a method not used, a contradiction not resolved or a recent change not yet examined. End your review by stating it clearly, because it justifies your research question.
Literature Review Checklist
- The scope and question are stated in the introduction.
- Your search is described if the brief requires it.
- Sections are organized by theme, not by source.
- Each paragraph discusses several studies together.
- Methods and limitations of key studies are evaluated.
- Agreements, disagreements and reasons are explained.
- The conclusion identifies a clear gap.
- Every source is cited and in the reference list.
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Frequently Asked Questions
It depends on the project. In a dissertation it is often 20 to 30 percent of the total; a standalone review follows its own word count.
Enough to represent the main research on your question. Undergraduate reviews may use 15 to 30 sources; postgraduate reviews often use more. Follow your brief.
Many briefs ask for sources from the last five to ten years, but include older landmark studies where they are still central.
Some disciplines allow it for describing your search or approach. Check your department's guidance.
An annotated bibliography discusses each source separately. A literature review synthesizes sources by theme into an argument.
Look for questions studies leave open, populations or settings not studied, conflicting findings and limitations authors themselves name.