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In the last decade, models of rational choice have chimed into the discussion on racial profiling, the use of race in stop and search decisions of the police. The models describe the behavior of motorists and the police and provide empirical tests to assess the question whether the police exhibit racial animus. However, existing studies have neglec...
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... The issue of homogeneity vs. heterogeneity also crops up in other dimensions. In another paper I show that aggregating police stop and search data across time and regions involves the danger of false conclusions when testing for racial prejudice with the established economic models (Ilić 2013). For example, when singling out troop G in AF's data, we cannot reject prejudice using AF's framework, a conclusion that drowns in their aggregate analysis. ...
In their article “An Alternative Test of Racial Prejudice in Motor Vehicle Searches: Theory and Evidence,” published in the American Economic Review in 2006, Shamena Anwar and Hanming Fang study racial prejudice in motor vehicle searches by Florida Highway Patrol officers (“troopers”). Their data include the race and ethnicity of the trooper and of the motorist stopped and possibly searched. A search is deemed successful if the trooper finds contraband in the vehicle. Using data on troopers and motorists of three race-ethnicity groups (white non-Hispanic, black, and white Hispanic, with others being dropped), Anwar and Fang compute nine trooper-on-motorist search rates and nine search-success rates. They present a model that exploits this information to test whether troopers go beyond statistical discrimination to racial prejudice. Irrespective of whether troopers exhibit racial prejudice, the model has a crucial testable implication, an implication that concerns the rank-order of the search and search-success rates. Anwar and Fang report that their data neatly fit this predicted rank-order implication with high statistical significance across the board, strongly supporting the soundness of the model. In turn, the model is applied to address the question of racial prejudice. They do not find evidence of racial prejudice, and neither do I—so the present critique does not arrive at results about prejudice contrary to their results. The present critique starts by reporting on my effort to replicate Anwar and Fang’s preliminary rank-order findings. I am unable to replicate two of their nine reported search-success rates, nor can I replicate the reported statistical significance of four of the six Z-statistics and one of the three χ2 test statistics for the rankings of the search-success rates. My new results imply that the empirical support for the model’s soundness is not what Anwar and Fang claim it to be. This problem of irreplicability is my primary point, but I then move on to another matter: My replications draw attention to a neglected statistical caveat in Anwar and Fang’s implementation of the empirical tests of racial prejudice. It turns out that the novel resampling procedure they employ does not provide robust results. I pinpoint the empirical source of this issue and, in an appendix, show how a simple extension to their method improves robustness. In another appendix I put forth an alternative randomization test that seems more appropriate when testing such resampled data.
For decades, racial profiling has been subject of intense debate in US jurisdiction. Recently, outcome tests based on economic models have contributed to the legal discourse. However, it is not readily obvious if and to what extent they also pertain to European jurisdiction, where racial profiling has only as of late stirred up controversy. In a comprehensive examination of their basic building blocks, this paper illustrates why the these tests are not particularly suited for the European case. The models are tailored to identify racial prejudice but are unfit to provide evidence of statistical discrimination, reflecting their adaption to the current US legal approach. A simple alternative test remedies this shortcoming and manages to inform the European jurisdiction.
