Evidence synthesis is a collective term for a variety of systematic and comprehensive literature research projects such as systematic reviews, scoping reviews, evidence maps, integrative reviews, mixed-methods reviews, realist/rapid reviews, umbrella reviews, and meta-analyses.
Evidence synthesis projects use explicit and rigorous methodology and follow reporting guidelines to reduce bias while gathering, assessing, characterizing and synthesizing literature for use in practice and policy decisions and for identifying future research agendas.
In their initial position statement (2020), the Evidence Synthesis International, a partnership of the major evidence synthesis organizations from various disciplines around the globe, states:
Evidence synthesis uses formal explicit rigorous methods to bring together the findings of studies already completed and to provide an account of the totality of what is known from that pre-existing research. Evidence synthesis clarifies what is known and not known about a research question. It uses research methods to provide a statement about an evidence base. It is therefore a crucial step in the use of research findings in personal and public decision making. (p. 1)