What do arrest statistics count?

To interpret the material in this Bulletin properly, the reader must have a clear understanding of what these statistics count. The arrest statistics report the number of arrests made by law enforcement agencies in a particular year—not the number of individuals arrested, nor the number of crimes committed. The number of arrests is not equivalent to the number of people arrested, because an unknown number of individuals are arrested more than once in the year. Nor do arrest statistics represent counts of crimes committed by arrested individuals, because a series of crimes committed by one individual may culminate in a single arrest, or a single crime may result in the arrest of more than one person. This latter situation, where many arrests result from one crime, is relatively common in juvenile law-violating behavior because juveniles are more likely than adults to commit crimes in groups. This is the primary reason why arrest statistics should not be used to indicate the relative proportion of crime committed by juveniles and adults. Arrest statistics are most appropriately a measure of flow into the criminal and juvenile justice systems.

Arrest statistics also have limitations for measuring the volume of arrests for a particular offense. Under the UCR Program, the FBI requires law enforcement agencies to classify an arrest by the most serious offense charged in that arrest. For example, the arrest of a youth charged with aggravated assault and possession of a controlled substance would be reported to the FBI as an arrest for aggravated assault. Therefore, when arrest statistics show that law enforcement agencies made an estimated 193,900 arrests of young people for drug abuse violations in 2004, it means that a drug abuse violation was the most serious charge in these 193,900 arrests. An unknown number of additional arrests in 2004 included a drug charge as a lesser offense.

The juvenile proportion of arrests exceeded the juvenile proportion of crimes cleared by arrest or exceptional means in each offense category, reflecting the fact that juveniles are more likely to commit crimes in groups and are more likely to be arrested than are adults

Data source: Crime in the United States 2004 (Washington, DC: U.S. Government Printing Office, 2005), tables 28 and 38 (updated 2/17/2006).

What do clearance statistics count?

Clearance statistics measure the proportion of reported crimes that were resolved by an arrest or other, exceptional means (e.g., death of the offender, unwillingness of the victim to cooperate). A single arrest may result in many clearances. For example, 1 arrest could clear 40 burglaries if the person was charged with committing all 40 of these crimes. Or multiple arrests may result in a single clearance if the crime was committed by a group of offenders. For those interested in juvenile justice issues, the FBI also reports information on the proportion of clearances that involved offenders under age 18. This statistic is a better indicator of the proportion of crime committed by this age group than is the arrest proportion, although there are some concerns that even the clearance statistic overestimates the juvenile proportion of crimes.

For example, the FBI reports that persons under age 18 accounted for 23% of all robbery arrests but only 14% of all robberies that were cleared in 2004. If it can be assumed that offender characteristics of cleared robberies are similar to those of robberies that were not cleared, then it would be appropriate to conclude that persons under age 18 were responsible for 14% of all robberies in 2004. However, the offender characteristics of cleared and noncleared robberies may differ for a number of reasons. If, for example, juvenile robbers were more easily apprehended than adult robbers, the juvenile proportion of cleared robberies would overestimate the juvenile responsibility for all robberies. To add to the difficulty in interpreting clearance statistics, the FBI’s reporting guidelines require the clearance to be tied to the oldest offender in the group if more than one person is involved in the crime.

In summary, while the interpretation of reported clearance proportions is not straightforward, these data are the closest measure generally available of the proportion of crime known to law enforcement that is attributed to persons under age 18.