Evidence synthesis is a type of secondary research created for use in evidence-based practice that combines information from a comprehensive range of sources to guide decisions and policies on specific issues.
This guide supports researchers of all experience levels and disciplines in understanding and conducting systematic and structured literature reviews and syntheses.
Over twenty review types exist. Key types are defined in the tabs above.
Recommended reading:
Identify, evaluate, and summarize the existing body of work produced by researchers, scholars, and practitioners on a particular topic (Fink, 2019). A literature review can be a standalone publication (journal article or book chapter) or can provide context for a new research study by serving as its introduction.
The research question is broad and methods are not described. Other members of the traditional review family include:
“A form of research synthesis that seeks to systematically search for, appraise and synthesize research evidence, using strategies to limit bias often adhering to guidelines on the conduct of a review.” (Booth et al., 2022). Generally speaking, a systematic review includes the following steps.
How you conduct each step and report findings depends on the guidelines you choose to follow.
See the Standards & Guidelines page for more information.
The research question for a systematic review is narrow and stated within a specific framework (PICO, PCC, PEO, etc.), methods are clearly described, and included studies are appraised. Other members of the systematic review family include but are not limited to:
Typically assess the potential size and scope of available research literature on a topic (Grant & Booth, 2009). Arksey & O'Malley (2005) propose a framework for conducting a scoping study which includes:
The research question is broad, methods are described, and in depth data extraction is performed.
JBI: What are scoping reviews? (6 minutes)
Examine a typically broad topic area to map out and categorize existing literature from which to propose future primary research or systematic review(s). (Grant & Booth, 2009; Sutton et al., 2019)
The research question is broader than for a scoping review, less in depth analysis.
Research questions for scoping and mapping reviews are broad and stated within frameworks, and methods are described.
Statistically combine results of multiple studies. They usually start with a systematic review and can be performed when multiple studies address the same question and measure the same outcome using similar or comparable methods (Booth et al., 2022).
JBI: What is meta analysis? (3 minutes)
| Review type | Purpose | Search | Coding/Appraisal | Synthesis |
|---|---|---|---|---|
| Narrative review | Topic overview | Varies in scope Not transparent |
Varies Not described |
Qualitative, sometimes unbalanced |
| Scoping/Mapping | Description of evidence base (Exploratory) |
Varies in scope Documented |
Categories only No appraisal |
Visual (tables or "maps") |
| Systematic review | In-depth synthesis to answer a specific question | Comprehensive Documented |
In-depth coding Required quality appraisal |
Qualitative |
| Meta-analysis | Numerical synthesis on studies on same specific question | Comprehensive Documented |
In-depth coding Required quality appraisal |
Quantitative |
Visit the Duke University Medical Center Library page to view a comprehensive comparison table of 14 review types.
This 8-phase framework guiding the lifecycle of a review project starts with Proposal (feasibility), it progresses through Protocol (methods), Production (preliminary findings), Paper (publication), Preservation (sharing), Promotion (stakeholder engagement), Impact tracking, and finally Update criteria.
Each of these phases involves eight core processes: Plan, Identify, Evaluate, Extract, Combine, Explain, Summarize, and Share, ensuring a systematic and comprehensive approach throughout the review project's life.
PIECCESS Framework was summarized from: Foster MJ and Jewell ST (Eds.) (2022) Piecing Together Systematic Reviews and Other Evidence Syntheses. (Medical Library Association Books Series) Lanham: Rowman & Littlefield. Dec 2022.
