First, police departments have much higher stop rates than sheriff’s departments, on average. Second, blacks have much higher stop rates than whites, across both types of agencies. Third, there is great variability in these statistics from agency to agency – for example, among sheriff’s departments, the mean black–white Stop Rate Ratio is 2.95, meaning that blacks are almost three times as likely as whites to be pulled over. However, the standard deviation is 1.93; this means there is tremendous range in outcomes from one agency-year to the next.
