The Logic of Profiling

Abstract

There are several strategies available to police "stopping" suspects. Most efficient is to stop only members of the group with the highest a priori probability of guilt; least efficient is indiscriminate stopping. The fairest profiling strategy is one that biases stops of different groups so that the absolute number of innocents stopped is equal for all groups. This strategy is close to maximally efficient, allows some sampling of low-crime subgroups , and seems fair by almost any criterion. Profiling is selecting or discriminating for or against individuals, based on characteristics that are not causally related to the behavior of interest. For example, age, sex or racial appearance are used as partial proxies for criminal behavior because crime rates differ among these groups. Old people, women and whites are less likely than young people, men and blacks to be perpetrators. Hence, preferentially 'stopping' young black males is likely to catch more criminals than stopping the same number of people at random.

Keywords: profiling, fairness, race, logic