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Assessing the Effect of Race Bias in Post-Traffic Stop Outcomes Using Propensity Scores

NCJ Number
Journal of Quantitative Criminology Volume: 22 Issue: 1 Dated: March 2006 Pages: 1-29
Greg Ridgeway
Date Published
March 2006
29 pages
Utilizing a propensity score technique, this study examined the extent to which race bias affected citation rates, search rates, and the duration of a traffic stop.
A race bias can reveal itself at every stage of a vehicle stop process, including the decision to stop, the decision to cite or warn, in the decision to search, and the amount of time to detain the vehicle. Within the Oakland Police Department, minority drivers, and African-American drivers in particular were treated equitably in terms of certain stop outcomes, such as citation rates and consent search rates. However, police officers rarely pat-searched White drivers similarly situated to African-American drivers. Race appeared to have the strongest influence on the duration of the stop. African-American drivers were less likely to have stops lasting less than 10 minutes. Using an analysis of traffic stop data from the City of Oakland, CA, this study focused on whether similarly situated drivers were treated equally regardless of race. Utilizing the propensity score technique, the study dissected the post-stop phase of the stop decision and assessed race bias in this decisionmaking point of the criminal justice process. The propensity score technique offers an analytical process that is more transparent than regression analysis for communicating results to those interested. Tables, and references