Table 1.

Descriptive statistics: Included studies, interventions, and outcome measures

Variable	M	SD	Min.	Max.	n imputeda
Study quality characteristics
Pretest effect sizeb	-0.07	0.26	-1.41	0.75	138
Average attrition	0.18	0.17	0	0.76	37
Differential attrition	-0.01	0.09	-0.27	0.22	37
Active control group (1 = yes)	0.37	0.49	0	1	0
General study characteristics
United States (ref.) (1 = yes)	0.79c	0.41	0	1	0
Great Britain (1 = yes)	0.05c	0.23	0	1	0
Scandinavia (1 = yes)	0.03c	0.16	0	1	0
Australia/New Zealand (1 = yes)	0.07c	0.25	0	1	0
Other country (1 = yes)	0.05c	0.23	0	1	0
Peer reviewed (1 = yes)	0.75	0.43	0	1	0
Publication year	2006.82	4.16	1995	2013	0
Participant characteristics
% Male	0.49	0.17	0	1	2
% White	0.78	0.23	-0.59d	1.24d	116
Mandated to treatment (1 = yes)	0.08	0.28	0	1	0
Intervention characteristics
PET (ref.) (1 = yes)	0.03	0.16	0	1	0
CBT (1 = yes)	0.08	0.28	0	1	0
MET/MI (1 = yes)	0.48	0.50	0	1	0
Feedback (1 = yes)	0.41	0.50	0	1	0
Intervention duration (in minutes)e	41.20	36.29	2	180	0
Outcome measuref
Frequency of useb (ref.) (1 = yes)	0.10c	0.30	0	1	0
Frequency of heavy useb (1 = yes)	0.21c	0.41	0	1	0
Quantity of useb (1 = yes)	0.38c	0.49	0	1	0
Peak consumptionb (1 = yes)	0.08c	0.27	0	1	0
Blood alcohol concentrationb	0.16c	0.37	0	1	0
Abstinence/mixedb (1 = yes)	0.08c	0.27	0	1	0
Assessment delay (in weeks)b	23.45	27.72	1	206.40	0

Notes: Min. = minimum; max. = maximum; ref. = referent category; PET = psychoeducational therapy; CBT = cognitive-behavioral therapy; MET/MI = motivational enhancement therapy/motivational interviewing; feedback = personalized feedback only.

^aNumber of observations imputed at effect size level (of 662 effect sizes);

^bdescriptive statistics estimated at effect size level. All other variables’ statistics estimated at study level (n = 73 independent studies);

^cmutually exclusive categories do not add to 100% because of rounding;

^dvalues below 0% and above 100% because of imputation;

^edegression analysis use a transformed variable, but the original, untransformed values are described here;

^falthough outcome measure type varied both between and within studies, the final model reported here includes only between-study effects for that moderator variable because of power concerns from too many parameters. Exploratory analyses including both between- and within-study effects resulted in substantially identical results.