Librarians and Information Scientists have identified 14 different types of evidence synthesis found in the medical, nursing, and scientific literature. Reviews range in breadth, depth, and quality of the work.
Literature Reviews, Narrative Reviews, and the like are more subjective, broader in scope, and use methods of inclusion or exclusion that are minimally or less defined.
Scoping Reviews, Systematic Reviews, Meta-Analyses and the like are more objective, narrower in scope, and use clearly defined and regimented methods of inclusion and exclusion. Scroll on to learn more!
A Systematic Review (click here for full guide) aims to systematically search for, appraise, and synthesize research evidence on a well-defined research question. It goes hand in hand with a meta-analysis, which statistically pools the results of individual studies to produce a single estimate of effect. In effect, it creates new knowledge by answering the scientific question through a robust, rigorous analysis of the existing research.
It’s important to know that a systematic review is:
Want to learn more? Head to this section of the LibGuide!
A Scoping Review (click here for full guide) is a type of evidence synthesis that aims to identify and map the evidence available on a particular topic. Scoping reviews can analyze what types of evidence (research trials, case reports, etc.) exist and are available to answer a question, clarify key concepts on a question or topic, identify knowledge gaps in research, and more.
It’s important to know that a scoping review is:
• A type of evidence synthesis that is held to rigorous standards, although it is not research.
• Requires a team authors (it can’t be done alone).
• Should involve the creation of and adherence to a protocol
• Should follow methodological guidance on conducting scoping reviews found in the field
• Should be reported in the literature according to established reporting guidelines
Want to learn more? Head to this section of the LibGuide!
A Literature Review, also known as a Narrative Review, is a type of evidence synthesis that examines recent or current literature on any a current topic of interest in a particular field or specialty. It can cover a wide range of subjects at various levels of completeness and comprehensiveness. This type of review aims to examine and summarize recent or current literature on a particular topic, in an effort to save clinicians time and effort from having to collect and review all the evidence for themselves.
It’s important to know that a literature review is:
• A type of evidence synthesis that is not held to rigorous standards, and it is not research.
• Can be done by a single author (but buddies are always better).
• Should involve the creation of a pre-determined plan for searching the literature
• Should follow the format of other narrative reviews done in that speciality.
• Should be reported in the literature so that it is clear that a planned method was followed and readers understand what was searched for and where the searches were conducted.
Want to learn more? Check out our guidelines and checklists!
Remember, a scoping review is NOT:
SRLibrarianProblems [@SRLibProblems]. Twitter, March 13, 2022, https://twitter.com/SRLibProblems/status/1503179100906610689
Read this article for more insight: Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach Citation: Munn Z, Peters MDJ, Stern C, Tufanaru C, McArthur A, Aromataris E. Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach. BMC Med Res Methodol. 2018 Nov 19;18(1):143. doi: 10.1186/s12874-018-0611-x. PMID: 30453902.
Read these blogs from systematic review resource platforms for more insight:
Understanding the Differences Between a Systematic Review vs Literature Review (From DistillerSR)
The difference between a systematic review and a literature review (From Covidence)
Sometimes, your topic or question is better suited to another type of evidence synthesis or review. There are 10 other main types of reviews, and over the years, different methodologies have been created so that there are subtypes. Librarians can help you decide if one of these types, which are less commonly found but still have great value, is the right type of review for your question.
Review the chart below to see the other ten types of evidence synthesis projects that exist in the literature. Click here to find the right Evidence Synthesis for you.
Reproduced from Grant, M. J. and Booth, A. (2009), A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26: 91-108. doi:10.1111/j.1471-1842.2009.00848.x
|
Label |
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 mode |
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 |
|
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 |
|
Mixed studies review/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 characterize both literatures and look for correlations between characteristics or use gap analysis to identify aspects absent in one literature but missing in the other |
|
Overview |
Generic term: summary of the [medical] literature that attempts to survey the literature and describe its characteristics |
May or may not include comprehensive searching (depends whether systematic overview or not) |
May or may not include quality assessment (depends whether systematic overview or not) |
Synthesis depends on whether systematic or not. Typically narrative but may include tabular features |
Analysis may be chronological, conceptual, thematic, etc. |
|
Qualitative systematic review/qualitative evidence synthesis |
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 |
|
State-of-the-art review |
Tend to address more current matters in contrast to other combined retrospective and current approaches. May offer new perspectives |
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 search and review |
Combines strengths of critical review with a comprehensive search process. Typically addresses broad questions to produce ‘best evidence synthesis’ |
Aims for exhaustive, comprehensive searching |
May or may not include quality assessment |
Minimal narrative, tabular summary of studies |
What is known; recommendations for practice. Limitations |
|
Systematized review |
Attempt to include elements of systematic review process while stopping short of systematic review. Typically conducted as postgraduate student assignment |
May or may not include comprehensive searching |
May or may not include quality assessment |
Typically narrative with tabular accompaniment |
What is known; uncertainty around findings; limitations of methodology |
|
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 |
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