Is the Shape of the Age-Crime Curve Invariant by Sex? Evidence from a National Sample with Flexible Non-parametric Modeling

Objectives: Prior theoretical scholarship makes strong assumptions about the invariance of the age-crime relationship by sex. However, scant research has evaluated this assumption. This paper asks whether the age-crime curve from age 12–30 is invariant by sex using a contemporary, nationally representative sample of youth, the National Longitudinal Survey of Youth 1997 cohort (NLSY97).

Methods: To address the limitations of the existing empirical literature, a novel localized modeling approach is used that does not require a priori assumptions about the shape of the age-crime curve. With a non-parametric method—B-spline regression, the study models self-report criminal behavior and arrest by sex using age as the independent variable, and its cubic spline terms to accommodate different slopes for different phases of the curve.

Results: The study shows that males and females have parallel age-crime curves when modeled with self-report criminal behavior variety score but they have unique age-crime in the frequency of self-report arrest. Group-based trajectory analysis is then used to provide a deeper understanding of heterogeneity underlying the average trends. The onset patterns by sex are quite similar but the post-peak analyses using the early onset sample reveal different patterns of desistance for arrest by sex.

Conclusions: The study found evidence of relatively early and faster desistance of arrest among females but little difference exists for the variety of criminal behaviors. Implications and future directions are discussed.