Table 2.

Weighted mean difference (between-groups) effect sizes and heterogeneity tests for interventions versus wait-list controls used to reduce alcohol consumption and alcohol-related problems among mandated college students.

Outcome	k	d+ (95% CI)	Heterogeneity
		Random effects	Q	p	I2(95% UI)
Short-term assessment (≤13 weeks)
Alcohol consumption
Quantity, per week/month	10	0.13 (0.02, 0.25)	9.70	.375	7 (0, 45)
Quantity, specific intervals/drinking day	8	0.08 (-0.05, 0.21)	6.85	.445	0 (0, 00)
Peak consumption	2	0.28 (-0.15, 0.71)	1.18	.277	15 (0, 54)
Frequency of drinking days	3	0.09 (-0.13, 0.31)	2.13	.345	6 (0, 35)
Frequency of heavy drinking	7	0.10 (-0.02, 0.23)	5.86	.439	0 (0, 00)
Peak BAC	7	0.20 (0.06, 0.33)	9.68	.139	38 (0, 74)
Typical BAC	5	0.16 (0.01, 0.31)	0.85	.932	0 (0, 51)
Alcohol-related problems	11	-0.02 (-0.15, 0.12)	7.82	.646	0 (0, 61)

Note. All dependent variables were examined for outliers (Emerson & Strenio, 1983). Of the 53 effect sizes, one outlier was detected for typical BAC (short-term). The unadjusted and adjusted (i.e., trimmed) weighted mean effect size-differed in magnitude for typical BAC (d_+unadjusted = 0.10, 95% CI = -0.03, 0.23, k = 6; d_+adjusted = 0.16, 95% CI = 0.01, 0.31, k = 5). The adjusted effect size is reported above. Positive weighted mean effect sizes (d₊) indicate that the treatment group reduced consumption or problems relative to the control group. k, number of interventions; d₊, weighted mean effect size; Q, heterogeneity statistic; I², consistency of effect sizes; CI, confidence interval; UI, uncertainty interval; BAC, blood alcohol concentration. Bold font indicates significant weighted mean difference effects.