Youjin Lee, Ph.D. Brown University Manning Assistant Professor of Biostatistics, will co-lead a National Science Foundation funded project with Nandita Mitra, Professor in Biostatistics and Epidemiology at the University of Pennsylvania. The project titled,  “Novel Approaches to Estimating the Causal Effect of Policy Interventions in the Presence of Spillovers" will develop novel causal inference methods to estimate spillover effects of public policy interventions.

Project summary: Policy interventions can spill over to portions of the population who are not directly exposed to the policy, but nonetheless live close to regions, such as cities or counties, that are directly affected. Failure to account for spillover effects can have serious implications on the evaluation of public policies, possibly underestimating or overestimating the overall effects of the policy. In this project, we will investigate the causal effects of policy interventions under varying patterns and degrees of policy exposure in neighboring regions. The methods to be developed will help researchers and policymakers better understand the effect of policy interventions on outcomes of interest in the presence of spillovers. The new methods will be used to assess the impact of the Philadelphia beverage tax on volume sales in Philadelphia and its surrounding counties that did not implement the tax.