Skip to Main Content
NAU Cline Library logo

Research Services: Evidence Synthesis Support

This guide provides information on review types for evidence synthesis, and includes tools to help decide which review type best serves your research needs.

What is Evidence Synthesis?

"Evidence synthesis is the interpretation of individual studies within the context of global knowledge for a given topic. These syntheses provide a rigorous and transparent knowledge base for translating research in decisions.  Essential to all evidence syntheses is the use of explicit and transparent methodology in the formation of the questions they address. The transparent methodology encompasses how studies are identified, selected, appraised, analyzed, and the strength of the evidence assessed to answer the questioned posed.

Evidence syntheses methods have been applied to a diverse and growing number of areas. Applications, include: education, crime and justice, international development, health care delivery, health technology assessment, veterinary medicine, pre-clinical drug development and toxicology, food safety, and environmental conservation. As equally diverse as the applications are the organizations that conduct, commission, and utilize the evidence synthesis."

Evidence Synthesis International. (n.d.). What is Evidence Synthesis. Retrieved January 25, 2021, from

Quick definitions for commonly used review types

A broad term referring to reviews with a wide scope and non-standardized methodology.

  • Search strategies, comprehensiveness, and time range covered vary and do not follow an established protocol.
  • Can be completed by one person. 
  • Analysis may be chronological, thematic, etc.

A methodical and comprehensive literature synthesis focused on a well-formulated research question.

• Aims to identify and synthesize all of the scholarly research on a particular topic, including both published and unpublished studies.

• Conducted in an unbiased, reproducible way (transparent) to provide evidence for practice and policy-making and to identify gaps in research.

• May involve a meta-analysis.

A statistical technique for combining the findings of quantitative studies to provide a more precise effect of the results.  

• Uses statistical methods to objectively evaluate, synthesize, and summarize results.

• May be conducted independently or as part of a systematic review.

Preliminary assessment of potential size and scope of available research literature. 

  • Seeks to identify research gaps and opportunities for evidence synthesis.
  • May critically evaluate existing evidence, but does not attempt to synthesize the results in the way a systematic review would.
  • May take longer than a systematic review.

Applies systematic review methodology within a time-constrained setting. 

  • Employs methodological “shortcuts” (limiting search terms for example) at the risk of introducing bias.
  • Useful for addressing issues needing quick decisions.
  • Assessment of what is already known. 

Reviews other systematic reviews on a topic.

• Often defines a broader question than is typical of a traditional systematic review.

• Most useful when there are competing interventions to consider.

Does a systematic review already exist on your topic?

The sources below are good places to search for systematic reviews or protocols for pending reviews. Contact a librarian for a more thorough search of published or in-progress systematic reviews.