The interrelationship of temporally distinct risk markers and the transition from childhood physical aggression to adolescent violent delinquency

A key aim of life course research is identification of whether turning point events such as marriage, entry into the work force or the military, grade retention, or joining a gang affect behavioral trajectories (Farrington & West, 1985; Hagan, MacMillan, & Wheaton, 1996; Lacourse, Nagin, Tremblay, Vitaro, & Claes, 2003; Nagin, Pagani, Tremblay, & Vitaro, 2003; Rutter, 1989; Sampson & Laub, 1993, 1996; Wheaton, 1990). The purpose of this chapter is to demonstrate an analytical strategy laid out by Nagin (2005) for analyzing such impacts in the context of the dual group-based trajectory model. The dual model was designed to analyze the developmental course of two distinct but related outcomes (Nagin & Tremblay, 2001). The model can be used to analyze connections between the developmental trajectories of two outcomes that are evolving contemporaneously (e.g., depression and alcohol use) or over different time periods (e.g., prosocial behavior in childhood and school achievement in adolescence). The latter type of application is the focus of this chapter.