| Critical review |
Aims to show that writer has extensively searched the literature & critically evaluated its quality. Provides a degree of analysis & conceptual innovation. Often results in hypothesis or model.
Example
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Seeks to identify the most significant items in the field |
No formal quality assessment. Attempts to evaluate according to contribution |
Typically narrative, may be conceptual or chronological |
Significant component: seeks to identify conceptual contribution to embody existing or derive new theory |
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Literature or Narrative review
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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 |
May be chronological, conceptual, thematic, etc. |
| Mapping review |
Map out and categorize existing literature from which to commission further reviews and/or primary research by identifying gaps in research literature.
Example
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Completeness of search depends on time/scope constraints |
No formal quality assessment |
May be graphical and tabular |
Characterizes quantity of literature, perhaps by study design and other key features. May identify need for primary or secondary research |
| Meta-analysis |
A study that systematically combines the results of quantitative studies & uses statistical analysis to provide a more precise effect of the results.
Example
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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 |
Combination of methods where one significant component is a literature review (usually systematic). In a review context it refers to a combination of review approaches, e.g. combining quantitative with qualitative research.
Example
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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 characterizes both literatures and look for correlations between characteristics or use gap analysis to identify aspects absent in one literature but present in the other. |
| Qualitative Systematic review |
Integrates or compares the findings from qualitative studies. Looks for themes or constructs that lie in or across individual qualitative studies.
Example
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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 |
Assesses what is already known about a policy or practical issue, by using systematic review methods to search and critically appraise existing research.
Example
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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 investigation of potential size and scope of available research. Aims to identify nature and extent of research evidence (usually including ongoing research). Requires following a protocol, e.g. Cochrane or Prisma.
Example
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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 |
| Systematic review |
Poses a well formulated research question to systematically search for, appraise and synthesize existing research evidence. Requires following a protocol, e.g. Cochrane or Prisma.
Example
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Aims for exhaustive, comprehensive searching |
Quality assessment may determine inclusion/ exclusion |
Typically narrative, may have tabular accompaniment |
What is known: recommendations for practice. What remains unknown; uncertainty around findings, recommendation for future research |
| Umbrella review |
A review compiling evidence from multiple reviews into one accessible and usable document. Focuses on broad condition or problem. Useful for gathering reviews of competing interventions. Analyses and highlights these interventions and their results.
Example
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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 |
