Generalising the Hit Rates Test for Racial Bias in Law Enforcement, With an Application to Vehicle Searches in Wichita*


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     The authors are grateful to the NSF for financial support under grants 0422863 and 0617507. The first author also gratefully acknowledges support in the form of a Sloan Research Fellowship. We thank Charles Manski, Steven Machin and an anonymous referee for helpful comments.


This article considers the use of outcomes-based tests for detecting racial bias in the context of police searches of motor vehicles. We characterise the police and motorist decision problems in a game theoretic framework, where police encounter motorists and decide whether to search them and motorists decide whether to carry contraband. Our modelling framework generalises that of Knowles et al. (2001). We apply the tests to data on police searches of motor vehicles gathered by the Wichita police department. The empirical findings are consistent with the notion that police in Wichita choose their search strategies to maximise successful searches.