I just finished reading a recent working paper by Martin Williams, titled “External validity and policy adaptation: From impact evaluation to policy design”. In this paper, Martin tackles the question – how will a policymaker apply evidence available to them to design a policy/programme that will fix a particular problem at hand? He first takes us through the ways in which we think of this currently – primarily by attempts to strengthen the external validity of evaluations – and points out the limitations of these approaches.

The central critique is that most of this thinking puts the evaluators/researchers at the centre and tries to devise ways in which the evidence generated by their research can be generalised beyond their specific study samples. This is at odds with what a policymaker needs in order to make decisions about how to use evidence from elsewhere to design a policy/programme for their specific context. — blog.wb.org/blogs