In this Bulletin "juvenile" refers to persons below age 18. This definition is at odds with the legal definition of juveniles in 1997 in 13 States -- 10 States where all 17-year-olds and 3 States where all 16- and 17-year-olds are defined as adults.
These FBI arrest data are counts of arrests within age of arrestee and offense categories from all law enforcement agencies that reported complete data for the calendar year. The proportion of the U.S. population covered by these reporting agencies ranged from 68% to 86% between 1980 and 1997.
Estimates of the number of persons in each age group in the reporting agencies' resident population assume that their population age profiles are like the Nation's. Reporting agencies' total populations were multiplied by the U.S. Bureau of the Census' most current estimate of the proportion of the U.S. population for each age group.