Literature review · 12 pages
Literature review & evidence synthesis
Clear, standards-grounded explainers for finding, appraising and synthesising the literature. Each page leads with a concise answer and draws on recognised frameworks — PRISMA, Cochrane, CASP, GRADE and PICO — before linking across to the wider CASRAI standards and dictionary.
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All 12 literature review & evidence synthesis pages
How to write a literature review
To write a literature review, define a clear scope and question, then search the literature systematically. Select sources against explicit criteria, appraise their quality, and synthesise findings by theme rather than source by source. Finally, write a structured, critical narrative and reference every source — analysis and argument, not summaries.
GuideLiterature review example
A good literature review example reads as a critical, thematically organised synthesis: it groups studies by concept, compares and evaluates them, and ends by naming a gap. A poor example merely summarises one source per paragraph with no connections. Reviews are usually organised thematically, sometimes chronologically, within an introduction, body and conclusion.
GuideTypes of literature review
The main types of literature review are narrative, systematic, scoping, integrative, umbrella, rapid and meta-analysis. They differ in aim and rigour: narrative reviews survey a field broadly; systematic reviews answer a focused question reproducibly; scoping reviews map the evidence; meta-analysis pools results statistically. The right type depends on your question, resources and time.
DefinitionNarrative review
A narrative review, also called a traditional review, is a flexible survey of the published work on a topic, selected and interpreted using the author’s expertise rather than a reproducible protocol. It suits broad context and synthesising a wide field, but its lack of method makes it more open to bias than a systematic one.
DefinitionIntegrative review
An integrative review synthesises evidence from studies of diverse methodologies — quantitative and qualitative, experimental and non-experimental — to build a comprehensive understanding of a phenomenon. Because it draws on varied designs, it suits defining concepts, building theory and reviewing complex topics, but combining heterogeneous data demands a careful, transparent and rigorous method.
DefinitionUmbrella review
An umbrella review, also called a review of reviews, synthesises the findings of multiple existing systematic reviews and meta-analyses on a topic. Sitting at the top of the evidence hierarchy, it offers a broad, high-level summary where many reviews already exist. Its quality depends entirely on the quality of the underlying reviews it draws upon.
DefinitionRapid review
A rapid review is a form of evidence synthesis that simplifies systematic review methods to deliver findings within a constrained timeframe, often weeks rather than months. It is used when decision-makers need timely evidence, such as in policy or public-health situations. The speed comes from streamlining steps, a transparent trade-off in comprehensiveness and bias.
How-toLiterature search strategy
To build a literature search strategy, break your question into core concepts, list keywords and synonyms for each, and add database subject headings. Combine synonyms with OR and concepts with AND, using truncation and phrase searching to focus results. Run it across several databases and record every term and date so it can be reproduced.
GuideBoolean search
Boolean search combines keywords using the operators AND, OR and NOT. AND narrows a search to records containing all terms; OR broadens it to any term; NOT excludes a term. Phrase searching, truncation and wildcards extend this, and brackets set the order in which operators apply. Together they build precise, reproducible literature searches.
How-toCritical appraisal
Critical appraisal is the structured process of assessing a study’s trustworthiness by examining three things: its validity (are the methods sound?), its results (what did it find, how precisely?), and its relevance (does it apply to your question?). CASP checklists guide appraisal of individual studies, while GRADE rates the certainty of a body of evidence.
How-toInclusion and exclusion criteria
Inclusion and exclusion criteria are the rules that decide which studies enter a review and which are left out. Inclusion criteria define the features a study must have — population, design, dates, language; exclusion criteria define what rules it out. Pre-specifying them keeps screening consistent and guards against selecting studies that suit the argument.
DefinitionConceptual framework
A conceptual framework is a structure — often a diagram — that sets out the key concepts or variables in a study and the relationships the researcher expects between them. Usually built for a specific study, it frequently draws on a broader theoretical framework. It guides the research question, the choice of variables and the analysis.
