How to Do Evidence Synthesis

Evidence synthesis is increasingly recognised as an essential element of the provision and use of expert advice in areas of public reasoning and decision-making. Synthesis here refers to an authoritative account of the best available knowledge in a field or fields, relevant to a question of policy interest and accessible to all interested audiences. Synthesis as a practice is well established in many areas of science and medicine. Although less frequent in the humanities, recent examples from funders and the British Academy illustrate increasing recognition of its importance. This article outlines why synthesis matters and, while pointing to some systemic challenges, shows how it can be done. It illustrates the findings from the literature with practical material from two recent projects led by the authors.