MPS, Self-efficacy, and Coping mean scores from piecewise analysis. MPS = Marijuana Problem Scale; ETX = end of treatment.
a: BRIEF vs. THERAPIST mean difference is significant (MPS 3M: t(173)=−2.82, p=0.005)
b: BRIEF vs. COMPUTER mean difference is significant (MPS 3M: t(173)=−2.13, p=0.03; Self-efficacy 3M: t(1.72)=2.03, p=0.04)