A systematic review is one type of evidence synthesis. The appropriate review type is dependent on the research question. Not all research questions are well-suited for systematic reviews.
Some common types of evidence synthesis:
* See "A typology of reviews: an analysis of 14 review types and associated methodologies" above for more detailed explanations.
Systematic review
- Definition: Seeks to systematically search for, appraise and synthesis research evidence, often adhering to guidelines on the conduct of a review.
- Search strategy: Aims for exhaustive, comprehensive searching.
Meta-analysis
- Definition: Technique that statistically combines the results of quantitative studies to provide a more precise effect of the results.
- Search strategy: Aims for exhaustive, comprehensive searching. May use funnel plot to assess completeness.
Scoping review
- Definition: Preliminary assessment of potential size and scope of available research literature. Aims to identify nature and extent of research evidence (usually including ongoing research).
- Search strategy: Completeness of searching determined by time/scope constraints. May include research in progress.
Literature review
- Definition: Generic term for general literature review. Published materials that provide examination of recent or current literature. Can cover a wide range of subjects at various levels of completeness and comprehensiveness. May include research findings
- Search strategy: May or may not include comprehensive searching.
Mapping review/systematic map
- Definition: Map out and categorize existing literature from which to commission further reviews and/or primary research by identifying gaps in research literature.
- Search strategy: Completeness of searching determined by time/scope constraints.
Mixed studies review/mixed methods review
- Definition: Refers to any combination of methods where one significant component is a literature review (usually systematic). Within a review context it refers to a combination of review approaches for example combining quantitative with qualitative research or outcome with process studies.
- Search strategy: Requires either very sensitive search to retrieve all studies or separately conceived quantitative and qualitative strategies.
Qualitative systematic review/qualitative evidence synthesis
- Definition: Method for integrating or comparing the findings from qualitative studies. It looks for ‘themes’ or ‘constructs’ that lie in or across individual qualitative studies
- Search strategy: May employ selective or purposive sampling
Rapid review
- Definition: Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research.
- Search strategy: Completeness of searching determined by time constraints.
Umbrella review
- Definition: Specifically refers to review compiling evidence from multiple reviews into one accessible and usable document. Focuses on broad condition or problem for which there are competing interventions and highlights reviews that address these interventions and their results.
- Search strategy: Identification of component reviews, but no search for primary studies.
Learn more about systematic reviews: