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Bottlenecks for Evidence Adoption
Stefano DellaVigna, Daniel Koshland, Sr. Distinguished Professor of Economics and Professor of Business Administration, UC Berkeley
Abstract: Governments increasingly use RCTs to test innovations, yet we know little about whether and how they incorporate the results into policy-making. We study 30 U.S. cities which collectively ran 73 RCTs in collaboration with a national Nudge Unit. Compared to most contexts, the barriers to adoption are low. Yet, the cities adopt a nudge treatment in follow-on communication, and thus change policy in response to evidence, in 27% of cases. As potential determinants of adoption we consider (i) the strength of the evidence in the RCT, (ii) features of the organization, and (iii) the experimental design. We find a limited impact of (i) strength of the evidence and (ii) city features; by far the largest predictor is (iii) whether the RCT was implemented as part of pre-existing communication, as opposed to in a new communication. The results differ from the predictions of both experts and practitioners, who over-estimate the extent of evidence-based adoption. We identify as a leading explanation organizational inertia: changes to pre-existing communications are more naturally folded into year-to-year city processes. Higher adoption for pre-existing communication is consistent also with evidence in other settings, including a re-analysis of Hjort et al. (2021). A survey of non-adopting cities in our sample suggests that a key barrier to adoption is insufficient leadership prioritization post RCT. (Co-authored with Woojin Kim and Elizabeth Linos)
Stefano DellaVigna is the Daniel Koshland, Sr., Distinguished Professor of Economics and Professor of Business Administration at the University of California, Berkeley. He specializes in Behavioral Economics (Psychology and Economics) and is a co-director of the Berkeley Initiative for Behavioral Economics and Finance. He has published in international journals such as the American Economic Review, the Quarterly Journal of Economics, the Journal of Finance, and the Journal of Labor Economics. He has been a Principal Investigator for an NSF Grant, an Alfred P. Sloan Fellow, and is a Distinguished Teaching Award winner. He was also a co-editor of the Journal of the European Economic Association (JEEA). His recent work has focused on the economics of the media, and in particular the impact on voting (through persuasion) and the study of conflicts of interest; the design of model-based field experiments, including the role of social pressure in charitable giving and voting, and the analysis of scientific journals and in particular editorial choices; the study of reference-dependence for unemployed workers.
