Table 4.

Multilevel Models Assessing Social Context of Substance Use Predicting Odds of SAM Use, by <21 and 21+ Years

			Total Sample	< 21 Years Old	21 Years and Older
			(n = 594 days)	(n = 302 days)	(n = 292 days)
Model 1	Level 1	Intercept	0.54 [0.28, 1.03]	0.79 [0.32, 1.96]	0.41 [0.15, 1.13]
		Alone	0.38 [0.18, 0.79]	0.34 [0.10, 1.13]	0.38 [0.14, 0.99]*
		Weekend	0.99 [0.61, 1.59]	0.58 [0.29, 1.17]	1.59 [0.81, 3.13]
	Level 2	Prop. Alone	0.72 [0.18, 2.91]	0.83 [0.13, 5.49]	0.57 [0.05, 6.07]
		Sex	1.49 [0.73, 3.07]	1.60 [0.61, 4.19]	1.35 [0.42, 4.34]
			Total Sample	< 21 Years Old	21 Years and Older
			(n = 463 days)	(n = 235 days)	(n = 228 days)
Model 2	Level 1	Intercept	0.51 [0.27, 0.95]*	0.94 [0.39, 2.29]	0.22 [0.08, 0.63]
		Number of People	1.02 [0.93, 1.12]	1.07 [0.94, 1.21]	0.97 [0.84, 1.12]
		Weekend	1.06 [0.62, 1.82]	0.52 [0.24, 1.14]	2.22 [0.98, 5.06]
	Level 2	Average Number of People	0.89 [0.77, 1.04]	0.99 [0.81, 1.21]	0.74 [0.57, 0.98]
		Sex	1.32 [0.63, 2.74]	1.08 [0.41, 2.86]	2.10 [0.59, 7.51]
Model 3	Level 1	Intercept	0.53 [0.28, 1.00]*	0.89 [0.37, 2.17]	0.30 [0.11, 0.86]*
		Others’ Level of Intoxication	1.01 [0.99, 1.02]	1.01 [0.99, 1.02]	1.01 [0.99, 1.03]
		Weekend	0.95 [0.55, 1.64]	0.48 [0.21, 1.07]	1.85 [0.82, 4.17]
	Level 2	Average Others’ Intoxication	1.02 [1.00, 1.04]	1.03 [1.00, 1.06]	1.01 [0.97, 1.05]
		Sex	1.42 [0.68, 2.97]	1.25 [0.48, 3.24]	1.84 [0.50, 6.81]

Note. Separate logistic multilevel models predict the odds of engaging in SAM use on a given day compared to days in which they used alcohol but not marijuana; results reflect odds ratios. Models were conducted separately for those under 21 years and 21+ years old. Weekends (Thursdays through Saturdays) were coded as 1 and weekdays (Sundays through Wednesdays) were coded as 0. Number of people and others’ level of intoxication refers to only days involving use with at least one other person.

^*p < .05