Diversification is a widely proposed policing reform, but its impact is difficult to assess. We used records of millions of daily patrol assignments, determined through fixed rules and preassigned rotations that mitigate self-selection, to compare the average behavior of officers of different demographic profiles working in comparable conditions. Relative to white officers, Black and Hispanic officers make far fewer stops and arrests, and they use force less often, especially against Black civilians. These effects are largest in majority-Black areas of Chicago and stem from reduced focus on enforcing low-level offenses, with greatest impact on Black civilians. Female officers also use less force than males, a result that holds within all racial groups. These results suggest that diversity reforms can improve police treatment of minority communities.

多样化是一项广泛提出的警务改革，但其影响很难评估。我们使用了通过固定规则和预先分配的轮换（可减轻自我选择）确定的每日数百万次巡逻任务的记录，以比较在可比条件下工作的不同人口统计特征人员的平均行为。相对于白人军官，黑人和西班牙裔军官进行的制止和逮捕要少得多，而且他们使用武力的频率更低，尤其是对付黑人平民。这些影响在芝加哥大多数黑人地区最为明显，其原因是人们对执行低级别犯罪的关注减少，这对黑人平民的影响最大。女警官使用的武力也比男警少，这在所有种族群体中都存在。