How to Write a Literature Review: From Source Selection to Critical Synthesis

What a Literature Review Actually Is

A literature review has three purposes:

1. Map the field: Show the reader what research exists on your topic
2. Identify patterns: Find agreements, contradictions, and trends across sources
3. Locate gaps: Identify what hasn't been studied yet — this often justifies your own research

The key word is synthesis. A summary tells the reader what each source says individually. A synthesis tells the reader what multiple sources say together — where they agree, where they conflict, and what the overall picture looks like.

Summary vs Synthesis: The Crucial Difference

Summary (what most students write):

Smith (2020) found that remote learning reduces engagement. Jones (2021) found that remote learning increases flexibility. Brown (2022) found that remote learning affects mental health.

This is a "shopping list" — each source gets its own sentence, with no connection between them.

Synthesis (what markers want):

While the flexibility benefits of remote learning are well-documented (Jones, 2021; Lee, 2022), engagement and wellbeing outcomes are less favourable. Smith (2020) and Brown (2022) both report declines in student engagement and mental health, though Smith's study was limited to first-year undergraduates, while Brown's longitudinal design provides stronger evidence for sustained effects. This tension between flexibility and wellbeing suggests that hybrid models, rather than fully remote delivery, may offer the best compromise — a position increasingly supported by institutional policy reviews (Taylor, 2023).

Notice the difference: the second version groups sources by theme, compares their findings, evaluates their methods, and builds toward a conclusion.

Types of Literature Review

Different assignments require different approaches:

Narrative Literature Review

The most common type for undergraduate assignments. You select relevant literature and organise it thematically to build an argument. You have some flexibility in which sources to include.

Systematic Literature Review

A rigorous, reproducible method with explicit search strategies and inclusion/exclusion criteria. Common in health sciences and evidence-based disciplines. You must document every step of your search process.

Scoping Review

Maps the breadth of literature on a topic without the strict methodology of a systematic review. Useful for identifying research gaps in emerging fields.

For most undergraduate essays and dissertations, you'll write a narrative literature review. This guide focuses primarily on that type.

Step 1: Develop a Search Strategy

Don't just type your topic into Google Scholar and hope for the best. A structured search strategy saves time and produces better results.

Choose Your Databases

• Google Scholar: Good starting point, but not comprehensive
• Your university library databases: JSTOR, PubMed, Scopus, Web of Science, PsycINFO, Business Source Complete — choose based on your discipline
• Reference lists: Check the bibliographies of key articles you've already found ("snowballing")

Build Your Search Terms

Use the PEO or PICO framework to break down your topic:

Combine with Boolean operators:

• "international students" AND "remote learning" AND engagement
• "online education" OR "distance learning" AND "student engagement"

Set Inclusion and Exclusion Criteria

Even for a narrative review, decide in advance:

• Date range: Last 10 years? 5 years? (Recent sources are usually preferred)
• Language: English only?
• Source type: Peer-reviewed journal articles only? Or also reports, theses, grey literature?
• Geography: UK-focused? International?

Document these decisions — your marker will want to see that your search was systematic, not random.

Step 2: Read and Organise with a Synthesis Matrix

Once you have your sources (aim for 15-30 for an undergraduate dissertation literature review, 8-15 for a standalone essay), use a synthesis matrix to organise them.

A synthesis matrix is a table where sources go in rows and themes go in columns:

This matrix helps you see patterns at a glance: Which themes come up repeatedly? Which sources agree? Which contradict? Where are the gaps?

Step 3: Choose Your Organisational Structure

Thematic (Recommended for most reviews)

Organise by theme, not by source. Each section covers one aspect of your topic, drawing on multiple sources.

Structure example:

1. Introduction (scope, purpose, search strategy)
2. Theme 1: Impact on student engagement
3. Theme 2: Flexibility and accessibility
4. Theme 3: Mental health and wellbeing
5. Theme 4: Institutional responses and hybrid models
6. Discussion of gaps and contradictions
7. Conclusion

Chronological

Organise by time period. Useful when the field has evolved significantly and the evolution itself is part of your argument.

Works well for: Historical policy analysis, the development of a scientific theory, changing social attitudes.

Methodological

Organise by research method. Useful when comparing qualitative and quantitative approaches to the same question.

Works well for: Methodology chapters in dissertations, comparing different research paradigms.

For most assignments, go with thematic. It demonstrates critical thinking and makes synthesis easier.

Step 4: Write Critically, Not Descriptively

This is where most students lose marks. Each paragraph in your literature review should do more than report — it should analyse and evaluate.

The Paragraph Formula

1. Topic sentence: State the theme or claim this paragraph explores
2. Evidence: Cite 2-4 sources that address this theme
3. Comparison: Show where sources agree or disagree
4. Evaluation: Assess the strength of the evidence (methodology, sample size, generalisability)
5. Link: Connect to your overall argument or the next paragraph

Example of a Strong Literature Review Paragraph

Student engagement in remote learning environments has been consistently identified as a concern, though the extent of the impact varies. Smith (2020) reported a 23% decline in participation among first-year undergraduates, while Brown (2022) found a sustained but smaller decline over two academic years across all levels. The discrepancy may reflect methodological differences: Smith's cross-sectional survey captures a snapshot of the initial transition to remote learning, whereas Brown's longitudinal design accounts for adaptation effects over time. Notably, neither study controlled for students' pre-existing digital literacy, which Wang (2021) identifies as a significant moderating factor. This suggests that engagement declines may be partly attributable to digital skills gaps rather than remote learning itself — a distinction with important implications for intervention design.

Language That Signals Critical Thinking

Step 5: Identify Gaps and Build Your Argument

A strong literature review doesn't just describe what exists — it identifies what's missing. Common types of gaps:

• Population gaps: "Most studies focus on domestic students; the experience of international students remains under-researched."
• Methodological gaps: "The reliance on self-report surveys limits the ability to draw causal conclusions."
• Geographical gaps: "The majority of studies are US-based; UK-specific evidence is scarce."
• Temporal gaps: "Pre-2020 studies may not reflect the post-pandemic reality of remote learning."
• Theoretical gaps: "Few studies have applied Self-Determination Theory to explain engagement patterns in online environments."

If your literature review is part of a dissertation, these gaps should directly justify your own research question.

Common Mistakes That Cost Marks

1. The "Shopping List" Review

Writing one paragraph per source with no connections between them. This is description, not synthesis. Your paragraphs should be organised by theme, not by source.

2. Lack of Critical Voice

Reporting what sources say without evaluating how well they say it. Every claim should be accompanied by an assessment of the evidence quality.

3. No Argument or Thread

A literature review is not a neutral summary. You should have a clear argument or narrative thread running through it — each section should build on the last.

4. Over-Reliance on a Few Sources

If one author appears in every paragraph, your review is too narrow. Aim for breadth of sources and diversity of perspectives.

5. Ignoring Contradictory Evidence

Don't cherry-pick sources that support your view. Acknowledging contradictions and explaining them is a sign of intellectual maturity — and it earns higher marks.

6. Citing Sources You Haven't Read

If you cite a study you found mentioned in another article but haven't actually read, that's a secondary citation. Use it sparingly and cite properly: "(Smith, 2020, cited in Jones, 2021)."

Literature Review Checklist Before Submission

• Organised by themes, not by individual sources
• Each paragraph discusses multiple sources, not just one
• Clear topic sentences for each paragraph
• Strengths and limitations of studies are discussed
• Contradictions between sources are acknowledged and explored
• Gaps in the literature are explicitly identified
• All sources are peer-reviewed or clearly justified
• Citations are consistent and correctly formatted
• A clear argument or narrative thread runs through the entire review
• The conclusion summarises the state of the field and identifies what's missing

The Bottom Line

A literature review tests three skills: your ability to find relevant sources, to understand what they collectively reveal, and to evaluate how strong the evidence actually is. The key shift is from reporting (what each source says) to synthesising (what they say together) to evaluating (how convincing the evidence is).

Use the synthesis matrix, organise by themes, and always ask: "What does the weight of evidence suggest — and where are the gaps?" If you can do that, you're writing a literature review, not a reading list.