Adolescents underwent a semi-structured interview of alcohol use behaviors using a version of the Substance Abuse Module of the Composite International Diagnostic Interview (Robins, Babor, & Cottler, 1987) that was modified to include questions covering alcohol misuse. One drink was defined as one bottle of beer, one glass of wine, or one ounce of hard liquor. To simplify our analysis, a single AAU factor score was generated using principal components factor analysis from three log10+1-transformed alcohol use outcomes: number of intoxications over the last six years (NumIntox), maximum number of drinks consumed in any one 24 hour period over the last six years (MaxCon), and the average number of drinks consumed on each drinking occasion during heaviest period of drinking over the last six years (HeavyAve). These outcomes were selected because they capture both frequency and intensity of alcohol use. The three alcohol use outcomes loaded between 0.889 and 0.973 on the largest factor (accounting for 88.2% of the total variance), supporting the use of a single composite variable as a measure of AAU. Prior to transformation, all three variables
