Cohort Variation in U.S. Violent Crime Patterns from 1960 to 2014: An Age–Period–Cohort-Interaction Approach
Previous research in criminology has overlooked that cohort effects on crime should be age-time-specific (Ryder in Am Sociol Rev 30(6):843–861, 1965) and consequently assumed cohort effects to be the same across the life course. The current study addresses these limitations by modeling cohort effects as the differential impacts of social change depending on age groups. With this new operationalization that is closely tied to Ryder’s conceptualization, we examine both inter-cohort differences and intra-cohort dynamics in violent crime. We use the age–period–cohort-interaction (APC-I) model developed by Luo and Hodges (Sociol Methods Res 2020) to analyze the UCR age-specific arrest statistics for robbery, aggravated assaults, and homicide from 1960 to 2014. Specifically, we estimate and test two types of cohort variation: average cohort deviations and life-course dynamics. Our findings reveal varying degrees of cohort deviations at different ages. The early boomers (born between 1945 and 1954) and the late boomers (born between 1955 and 1964) demonstrate different intra-cohort dynamics of robbery arrest, and the violence epidemic cohorts’ (born between 1975 and 1984) high risks of homicide arrest appear to be driven by cohort deviations at young ages. The APC-I framework introduced in this study provides new insights into the dynamic aspect of cohort effects on violent crime that have not been examined in the criminological literature. Criminological studies on cohort effects would benefit by shifting away from the problematic assumption of constant and additive cohort effects to the dynamic and interactive approach represented by the APC-I framework.