At Time 2, participants were asked how old they were when they began drinking regularly. More specifically, they were asked “At what age did you begin to drink regularly; that is, drinking at least once a month for 6 months or more?” They also were asked how old they were when they first used tobacco, and when they first used marijuana. Because the distributions of these variables were skewed, they were trichotomized. For tobacco use onset, the categories were early onset=14 years of age or younger, middle/normative onset=15-19 years of age, and late onset=over 20 years of age. For regular drinking and marijuana use onset, the categories were early onset=16 years of age or younger, middle/normative onset=17-22 years of age, and late onset=over 22 years of age.
