dichotomization approach may be arbitrary. In recent studies of natural trajectories of alcohol use among adolescents and college students, heterogeneous subgroups are empirically identified based on their trajectories over time (e.g., Sher, Gotham, & Watson, 2004). The same methodology may also be adopted for evaluation studies to document subgroups with distinctive profiles of change over time post intervention and to examine predictors and moderators of change.
