. Author manuscript; available in PMC: 2019 Feb 23.

Published in final edited form as: Subst Use Misuse. 2017 Aug 31;53(3):521–531. doi: 10.1080/10826084.2017.1342660

Table 2.

Regression model of past 30-day marijuana use with age-interactions, stratified by gender.

	Male	Female
Main effects
Intercept	0.89 (0.32)^∗∗	1.01 (0.25)^∗∗∗
Race (Black)	(Ref)	(Ref)
Race (White)	0.30 (0.17)	0.36 (0.13)^∗∗
Race (Multi)	0.02 (0.45)	0.06 (0.28)
Baseline SES score (divided by 10)	0.06 (0.06)	− 0.11 (0.05)^∗
Baseline family structure	− 0.21 (0.14)	0.05 − (0.11)
Friend drug use	0.97 (0.10)^∗∗∗	1.16 (0.09)^∗∗∗
Friend aggression	0.12 (0.06)^∗	0.06 (0.07)
Parental support	− 0.19 (0.06)^∗∗	− 0.04 (0.03)
Age-interactions
Friend drug use	− 0.03 (0.01)^∗∗	− 0.05 (0.01)^∗∗∗
Friend aggression	N/A	− 0.00 (0.01)
Parental Support	0.01 (0.00)^∗	N/A
Model statistics
R²	0.52	0.47
Random effect variance	1.10	0.59
Residual variance	2.46	1.61

Notes:

^∗

p < .05;

^∗∗

p < .01;

^∗∗∗

p < .001.

Age was centered by its minimum (approximately 14.8 years old), so that mean effects for friend drug use, friend aggression, and parental support reflect effects at age 14.8, and interactions reflect differences per-year after that age. The main effect of age (as a nonparametric trend) was included in the model but not shown here.