Books

Books : reviews

Nancy Cartwright, Jeremy Hardie.
Evidence-Based Policy: a practical guide to doing it better.
OUP. 2012

For the last twenty or so years, policymakers have been enjoined to base their recommendations on evidence. That is now uncontroversial to the point of triviality—of course policy should be based on the facts. But are the methods that policy makers are supposed to rely on to gather and analyze evidence the right ones? In Evidence-Based Policy, Nancy Cartwright and Jeremy Hardie explain that the dominant methods now in use—methods that imitate standard practices in medicine, like randomized control trials—do not work. They fail, Cartwright and Hardie contend, because they do not enhance our ability to predict whether policies will be effective. Current guides for the use of evidence tend to rank scientific methods according to the degree of trustworthiness of the evidence they produce. That is valuable in certain respects, but it provides little advice about how to think about putting such evidence to use. Evidence-Based Policy focuses on showing policymakers how to use evidence effectively. It also explains what types of information are most necessary for making reliable policy and offers lessons on how to organize that information.