Cincinnati Police Department Traffic Stops

Applying RAND's Framework to Analyze Racial Disparities

by Greg Ridgeway


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In 2002, the Cincinnati Police Department (CPD), through a collaborative agreement, joined with other organizations to improve police-community relations. As a part of this agreement, Cincinnati asked RAND to evaluate progress toward achieving the agreement's goals. This monograph focuses on three assessments that evaluate whether data on traffic stops exhibit evidence of racial profiling: (1) an assessment of whether there is a department-wide pattern of bias against black drivers in the decision to stop a vehicle, (2) an assessment of the fraction of CPD officers who disproportionately stop black drivers compared to other officers patrolling the same neighborhoods at the same time, and (3) an assessment of racial biases in post-stop outcomes, including stop duration, citation rates, and search rates. RAND has developed a framework for conducting each of these assessments, and this monograph describes the associated methodology in detail. The framework removes the effect of other plausible explanations for racial differences, particularly adjustments for when, where, and why stops occur, to isolate race's effect from that of other factors on the decision to stop, cite, and search vehicles. In addition to providing an analysis of Cincinnati's traffic stops for 2008, the framework offers direction for Cincinnati and other communities concerned about racial profiling to assess their traffic-stop data.

Table of Contents

  • Chapter One


  • Chapter Two

    Is There a Department-Level Racial Pattern in Initiating Vehicle Stops?

  • Chapter Three

    Do Individual Officers Appear to Have Racial Biases in Their Decisions to Stop?

  • Chapter Four

    Are There Racial Disparities in the Outcomes of Stops?

  • Chapter Five

    Conclusions and Implications

  • Appendix A

    Details of the Propensity-Score Weighting Approach

  • Appendix B

    Estimating False-Discovery Rates

  • Appendix C

    Detailed Tables for Post-Stop Outcomes

  • Appendix D

    Comments from the Parties on the Report

The research described in this report was sponsored by the City of Cincinnati and was conducted under the auspices of the RAND Center on Quality Policing within the Safety and Justice Program of RAND Infrastructure, Safety, and Environment (ISE).

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