How Do Policymakers Update Their Beliefs?

Abstract

Evidence-based policymaking requires not only evidence, but also for policymakers to update their beliefs based on that evidence. We examine how policymakers, researchers, and development practitioners update in response to results from academic studies, using a unique opportunity to run an experiment on policymakers. We find evidence of “variance neglect”, a bias similar to extension neglect in which confidence intervals are ignored. We also find evidence of asymmetric updating on good news relative to one’s prior beliefs. Finally, we test whether providing different types of information can mitigate the observed biases.