Toward an Understanding of the Political Economy of Using Field Experiments in Policymaking

Field experiments provide the clearest window into the true impact of many policies, allowing us to understand what works, what does not, and why. Yet, their widespread use has not been accompanied by a deep understanding of the political economy of their adoption in policy circles. This study begins with a large-scale natural field experiment that demonstrates the ineffectiveness of a widely implemented intervention. We leverage this result to understand how policymakers and a representative sample of the U.S. population update their beliefs of not only the policy itself, but the use of science and the trust they have in government. Policymakers, initially overly optimistic about the program's effectiveness, adjust their views based on evidence but show reduced demand for experimentation, suggesting experiment aversion when results defy expectations. Among the U.S. public, support for policy experiments is high and remains robust despite receiving disappointing results, though trust in the implementing institutions declines, particularly in terms of perceptions of competence and integrity. Providing additional information on the value of learning from unexpected findings partially mitigates this trust loss. These insights, from both the demand and supply side, reveal the complexities of managing policymakers' expectations and underscore the need to educate the public on the value of open-mindedness in policy experimentation.