AN IMPROVED METHODOLOGY FOR ANALYZING AGE-ARREST PROFILES - APPLICATION TO A WESTERN-AUSTRALIAN OFFENDER POPULATION

A new methodology for displaying and analyzing ''arrest profiles'' of a population of offenders is illustrated on a data set containing info rmation on all arrests made in the jurisdiction of the state of Wester n Australia in the 12-year period 1 April 1984 to 31 December 1995. Th e arrest profile shows the number of arrests accumulated by an individ ual offender as a function of the age at which each arrest took place. This provides a summary of the ''arrest careers'' of the individuals in the population and facilitates comparisons between groups of intere st in the population, such as sex and race groups. In particular, it e nables comparisons to be made between cohorts of offenders defined by the age-at-onset of their offending. For the Western Australian popula tion analyzed here we find large differences between sex and race (Abo riginal or non-Aboriginal) groups, and also between age-at-onset cohor ts, and we place these differences in the context of current criminolo gical discussions which posit that higher mean numbers of offenses wil l be committed by early career starters.