Evidence synthesis involves analyzing and combining studies to create a comprehensive understanding of a topic. It is used across various fields such as medicine, policy making, education, criminal justice, food safety, and conservation. The aim of evidence synthesis is to identify and synthesize all of the scholarly research on a particular topic, including both published and unpublished studies. By integrating evidence from multiple studies, it provides a clearer picture of an issue, aiding researchers, individuals, and organizations in making informed decisions. Evidence syntheses are conducted in an unbiased, reproducible way to provide evidence for practice and policy-making, as well as to identify gaps in the research.
Systematic Reviews are the most common type of evidence synthesis, but other forms of synthesis projects include scoping reviews, evidence maps, rapid reviews, umbrella reviews, and meta-analyses.
Campbell, J. (2024). Evidence synthesis. Salem Press Encyclopedia.
| Literature Review | Methodological Stage | Evidence Synthesis |
| Introduces context and current thinking, often without a specific question, is general and covers several aspects of a topic. | Focus of review | Uses a precise question to produce evidence to underpin a piece of research. A stand-alone piece of research, it should be conducted prior to undertaking further research, particularly in higher degree theses. |
| Finds papers through a fairly random process, usually searching only a few databases. Use of grey literature common, but not usually systematic. | Methods for data collection | Searches of several specified databases using precise search terms; a similar systematic search of grey literature sometimes included, depending on the question. |
| Papers are read, ‘take home’ messages used in the review. | Methods for data extraction | Data extraction tool used to identify precise pieces of information; two or more researchers undertake data extraction. |
| Anything up to 150 papers or more. | Number of papers included in review | Usually less than 50 papers; often fewer than 10. |
| Writer interprets the meaning of the results. | Methods for data analysis | Recognised, referenced, methods for data analysis; includes analysis of methods, rigour of conduct of research, strength of evidence, and so on. |
| Prose paper, occasionally supported with diagrams. | Methods for data presentation | PRISMA/CONSORT or similar chart/table of included papers. |
| Not suitable for Journal publication. | Publication | Might be suitable for Journal publication. |
| Actions/directions informed by evidence of various kinds drawn from included papers. | Outcome | Actions/directions are based on evidence from reviewed papers. |
Robinson, P. and Lowe, J. (2015), Literature reviews vs systematic reviews. Australian and New Zealand Journal of Public Health, 39: 103-103. https://doi.org/10.1111/1753-6405.12393