Dean Knox: Monitoring Racial Bias in Police Traffic Enforcement with Proxies of Driver Behavior

Title: Monitoring Racial Bias in Police Traffic Enforcement with Proxies of Driver Behavior
 

Abstract: Decades of work has sought to assess whether police traffic enforcement is discriminatory by comparing the racial composition of those who are stopped to some external benchmark, such as local residents in a police jurisdiction. Such "benchmark analyses" have been criticized by statisticians and law-enforcement officials alike for failing to accurately represent the population actually at risk of police traffic stops—namely, individuals engaged in dangerous driving. In this work, we present a causal framework for benchmark analysis that clarifies implicit assumptions in prior work and demonstrates how these assumptions can be empirically falsified. By drawing connections between benchmark analysis and a recent literature on negative control outcomes, we derive new estimators and partial identification results to address common statistical challenges that arise in benchmark analyses. Among other challenges, we consider scenarios where (1) "false positives" induce distortions in benchmark composition; (2) civilian race cannot be directly observed and must instead by inferred from surnames listed on citations; and (3) officer decisions lead drivers to modify the behavior that is captured by benchmarks. Applications across multiple jurisdictions illustrate a variety of plausible benchmark data sources including speeding cameras, traffic collisions, and DUI checkpoints.
 

Bio: Dean Knox is a computational social scientist and an assistant professor in Operations, Information, and Decisions and Statistics and Data Science at the Wharton School of the University of Pennsylvania. He is an Andrew Carnegie Fellow and the inaugural recipient of Science magazine's NOMIS early career award for interdisciplinary research. His research has appeared in Science, the Proceedings of the National Academy of Sciences, the Journal of the American Statistical Association, and the American Political Science Review. He has advised the Department of Justice, the American Civil Liberties Union, and the NAACP Legal Defense Fund on civil-rights data analysis.