UCR and Arrest Rates
UCR data are based on police reports. For this reason, the FBI calls the offenses on which it provides data “crimes known to the police.” The crimes known to the police, then, become the “official” number of crimes that the police report to the UCR Program, and that the UCR Program, in turn, reports to the public. How do police departments find out about crimes—the crimes known to the police? These data are based on citizen complaints of crime. For each crime reported, the police tell the FBI whether someone was arrested for that crime or whether the crime was cleared for some other reason—for instance, the death of the main suspect.
For each arrest that occurs, the police report to the FBI the arrestee’s age, gender, and race. When someone is arrested for a crime, that crime is counted as being “cleared by arrest.” Overall, statistics suggest that the police clear about 20% of all index crimes, although the clearance rate varies by the type of crime (Barkan and Bryjak, 2004).
However, the annual Uniform Crime Reports do provide information about the number of crimes in each category cleared by arrest.