Abstract

Evaluation research is tortured by time constraints. The policy cycle revolves quicker than the research cycle, with the result that `real time' evaluations often have little influence on policy making. As a result, the quest for evidence-based policy has turned increasingly to systematic reviews of the results of previous inquiries in the relevant policy domain. However, this shifting of the temporal frame for evaluation is in itself no guarantee of success. Evidence, whether new or old, never speaks for itself. Accordingly, there is debate about the best strategy of marshalling bygone research results into the policy process. This article joins the imbroglio by examining the logic of the two main strategies of systematic review: `meta-analysis' and `narrative review'. Whilst they are often presented as diametrically opposed perspectives, this article argues that they share common limitations in their understanding of how to provide a template for impending policy decisions. This review provides the background for Part II of the article (to be published in the next issue, Evaluation 8[3]), which considers the merits of a new model for evidence-based policy, namely `realist synthesis'.