Structural ageing and Australian crime trends : an exploration of the Easterlin hypothesis and the nature of the age-crime pattern

This thesis explores Richard Easterlin's theories regarding the association between structural ageing and crime, and its relation to the age-crime pattern, in a three-tiered analysis of Western Australian and South Australian apprehension trends. Easterlin (1987a) proposes two expressions of an age structure-crime pattern: cohort density and age composition. The cohort density expression suggests that, in comparison to smaller birth cohorts, large birth cohorts will engage in higher levels of criminal activity because they experience higher levels of internal competition, and thus, relative disadvantage. The age composition expression suggests a concomitant decline in young persons' share of the population age structure and crime because, in comparison to older persons, young persons make a more sizeable contribution to a population's crime levels. These arguments have not previously been investigated for Australia. Such analysis is appropriate, as official Australian crime statistics reflect the age-crime pattern (i.e. that individual offence levels peak around age 15-24 years and decline thereafter), and the population is ageing structurally. Initially, the state of the age-crime pattern is assessed through distribution and correlation analysis. The findings indicate that the Australian age-crime pattern is diminishing; a decline in young persons' share of all apprehensions, and an upward shift in the age distribution of offenders, is unfolding more or less simultaneously with change in population share. Cohort-specific departures from the age-crime pattern (i.e. whether or not the cohort has experienced declining apprehensions levels as it has aged, thus extending its participation in crime beyond the young crime-prone ages) are then identified by organising age-specific apprehension rates by birth cohort over time. Cohort analysis reveals that high cohort density is a potential source of variance in the age-crime pattern, and that departures from the age-crime pattern have been more sizeable (and frequent) for the younger, larger 'baby bust' cohorts (the residential Australian population born 1968-74). Finally, apprehension rates are standardised (and decomposed) for change in age structure, population size, and apprehension rates. These analyses show that structural ageing is constraining apprehension levels; its influence is generally greater than that of population growth, but lower than underlying change in apprehension levels which typically have the largest effect. Overall, therefore, the thesis finds Easterlin's propositions to be supported, with Australian crime trends having been influenced by both cohort density and age composition effects. However, there are some differences across gender, offence categories, and period, suggesting that, like the underlying age-crime pattern, the association between structural ageing and crime is not rigidly invariant.