Table 3.

Marijuana Use Motives Predicting Substance Use

	ΔR²	t (each predictor)	β	sr²	p
Criterion Variable: Marijuana Use1
Step 1	.13				.001
Gender4		.16	.01	.00	ns
Age at Onset of Marijuana Use		−2.45	−20	.04	.015
Tobacco Use		2.75	.22	.05	< .01
Alcohol Consumption		1.42	.12	.01	ns
Step 2	.30				< .001
MMM – Enhancement5		3.85	.33	.09	< .001
MMM – Conformity6		−2.91	−20	.05	<.01
MMM – Expansion7		.63	.05	.00	ns
MMM – Coping8		1.77	.14	.02	ns
MMM – Social9		2.10	.17	.03	< .05
Criterion Variable: Tobacco Use2
Step 1	.12				.001
Gender		−.57	−.04	.00	ns
Age at Onset of Marijuana Use		−2.49	−.20	.04	.01
Marijuana Use		2.75	.22	.05	< .01
Alcohol Consumption		−1.38	−.11	.01	ns
Step 2	.06				.05
MMM – Enhancement		.63	.06	.00	ns
MMM – Conformity		.65	.05	.00	ns
MMM – Expansion		.96	.09	.00	ns
MMM – Coping		2.33	.22	.03	< .05
MMM – Social		−1.15	−.11	.00	ns
Criterion Variable: Alcohol Consumption3
Step 1	.12				.001
Gender		−3.96	−.31	.10	< .001
Age at Onset of Marijuana Use		−.99	−.08	.00	ns
Marijuana Use		1.42	.12	.01	ns
Tobacco Use		−1.38	−.11	.01	ns
Step 2	.02				ns
MMM – Enhancement		1.12	.12	.00	ns
MMM – Conformity		.65	.06	.00	ns
MMM – Expansion		−.99	−.09	.00	ns
MMM – Coping		.91	.09	.00	ns
MMM – Social		−.33	−.03	.00	ns

Note: β = standardized beta weight

sr² = Squared semi-partial correlation

¹Marijuana History Questionnaire – Marijuana Use, Past 30 Days

²Smoking History Questionnaire – Number of Cigarettes Smoke per Day

³Alcohol Assessment: Alcohol Volume × Frequency of Use

⁴Dichotomous Variable (1 = male; 2 = female)

⁵Marijuana Motives Measure – Enhancement Factor

⁶Marijuana Motives Measure – Conformity Factor

⁷Marijuana Motives Measure – Expansion Factor

⁸Marijuana Motives Measure – Coping Factor

⁹Marijuana Motives Measure – Social Factor