‘Black magic’ and ‘gold dust’: the epistemic and political uses of evidence tools in public health policy making

Concerns about the limited influence of research on decision making have prompted the development of tools intended to mediate evidence for policy audiences. This article focuses on three examples, prominent in public health: impact assessments; systematic reviews; and economic decision-making tools (cost-benefit analysis and scenario modelling). Each has been promoted as a means of synthesising evidence for policy makers but little is known about policy actors’ experiences of them. Employing a literature review and 69 interviews, we offer a critical analysis of their role in policy debates, arguing that their utility lies primarily in their symbolic value as markers of good decision making.