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Systematic Reviews

This is a guide for learning about systematic reviews.

Types of Reviews

These are just some of the types of evidence synthesis: 

  • Systematic review 
  • Meta-analysis 
  • Scoping review 
  • Rapid review

**For more information on different review types, please see Grant, M. and Booth, A. (2009). A typology of reviews: an analysis of 14 review types and their associated methodologiesHealth Information and Libraries Journal, 26(2), 99-108. 10.1111/j.1471-1842.2009.00848.x or the Types of Review page in this guide. 

What type of review should you conduct?

Not sure what type of review would best fit your research question? Take a look at these tools, which can help guide you through the process of selecting a review type to pursue. 

Review types - a tabular overview

 

  Description Search  Appraisal Synthesis  Analysis 
Critical Review  Aims to demonstrate writer has extensively researched literature and critically evaluated its quality. Goes beyond mere description to include degree of analysis and conceptual innovation. Typically results in hypothesis or model
 
Seeks to identify most significant items in the field No formal quality assessment. Attempts to evaluate according to contribution Typically narrative, perhaps conceptual or chronological Significant component: seeks to identify conceptual contribution to embody existing or derive new theory
Literature Review  Generic term: published materials that provide examination of recent or current literature. Can cover wide range of subjects at various levels of completeness and comprehensiveness. May include research findings May or may not include comprehensive searching May or may not include quality assessment Typically narrative Analysis may be chronological, conceptual, thematic, etc.
Mapping Review/Systematic Map  Map out and categorize existing literature from which to commission further reviews and/or primary research by identifying gaps in research literature Completeness of searching determined by time/scope constraints No formal quality assessment  May be graphical and tabular  Characterizes quantity and quality of literature, perhaps by study design and other key features. May identify need for primary or secondary research
Meta-analysis  Technique that statistically combines the results of quantitative studies to provide a more precise effect of the results Aims for exhaustive, comprehensive searching. May use funnel plot to assess completeness Quality assessment may determine inclusion/exclusion and/or sensitivity analyses Graphical and tabular with narrative commentary Numerical analysis of measures of effect assuming absence of heterogeneity
Mixed Methods Review  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 Requires either very sensitive search to retrieve all studies or separately conceived quantitative and qualitative strategies Requires either a generic appraisal instrument or separate appraisal processes with corresponding checklists Typically both components will be presented as narrative and in tables. May also employ graphical means of integrating quantitative and qualitative studies Analysis may characterise both literatures and look for correlations between characteristics or use gap analysis to identify aspects absent in one literature but missing in the other
Qualitative Systematic Review  Method for integrating or comparing the findings from qualitative studies. It looks for ‘themes’ or ‘constructs’ that lie in or across individual qualitative studies May employ selective or purposive sampling Quality assessment typically used to mediate messages not for inclusion/exclusion Qualitative, narrative synthesis Thematic analysis, may include conceptual models
Rapid Review  Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research Completeness of searching determined by time constraints Time-limited formal quality assessment Typically narrative and tabular Quantities of literature and overall quality/direction of effect of literature
Scoping Review  Preliminary assessment of potential size and scope of available research literature. Aims to identify nature and extent of research evidence (usually including ongoing research) Completeness of searching determined by time/scope constraints. May include research in progress No formal quality assessment Typically tabular with some narrative commentary Characterizes quantity and quality of literature, perhaps by study design and other key features. Attempts to specify a viable review
State-of-the-art Review  Tend to address more current matters in contrast to other combined retrospective and current approaches. May offer new perspectives on issue or point out area for further research Aims for comprehensive searching of current literature No formal quality assessment Typically narrative, may have tabular accompaniment Current state of knowledge and priorities for future investigation and research
Systematic Review  Seeks to systematically search for, appraise and synthesize research evidence, often adhering to guidelines on the conduct of a review Aims for exhaustive, comprehensive searching Quality assessment may determine inclusion/exclusion Typically narrative with tabular accompaniment What is known; recommendations for practice. What remains unknown; uncertainty around findings, recommendations for future research

Umbrella Review 

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 Identification of component reviews, but no search for primary studies

Quality assessment of studies within component reviews and/or of reviews themselves

Graphical and tabular with narrative commentary What is known; recommendations for practice. What remains unknown; recommendations for future research

Reproduced from Grant MJ and Booth A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologiesHealth Information and Libraries Journal, 26(2), 91-108. doi: 10.1111/j.1471-1842.2009.00848.x