'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 policymakers 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