Figure 2.

Smooth estimates of the age-varying regression coefficient relating past 30-day-marijuana use to each social influence variable, stratified by gender, controlling for within-individual correlation using a random intercept. Note 1: In the modeling used to produce these trajectories, age is treated as a continuous variable, as opposed to the descriptive plot in Figure 1, which bins age in categories. Note 2: The y-axis in each plot is the estimated regression coefficient relating that the corresponding variable to past 30-day marijuana use. For example, in the left panel, the coefficient of friend drug use decreases linearly from about 1.2 to 0.3 among females from age 15 to 33.