Sex, race, and age were assessed at baseline. Age-of-onset information was available for five milestones that occur between first exposure to alcohol and alcohol-related problems/alcohol dependence: first drink more than a sip of alcohol; first got drunk; first drank at least once a month for 6 months or more; first drank 5 or more drinks at least one day a week; first drank at least five drinks every day for a period of two straight weeks. Based on concerns about the validity of responses indicating consumption at an extremely young age, age was bottom coded as “six and under.” For analyses considering age of onset (age of first drink) as a moderator, the variable was coded as early (age 10 or less; 24.6%), moderate (age 11–13; 47.4%), and late (age 14+; 28.0%). Age 14 is frequently used to classify “later” age of onset [7,10]; these cutpoints also correspond to ages of transition in schools (middle school at age 11; high school at age 14). For analyses using race as a moderator/grouping variable, differences are examined for Whites, Blacks, and Hispanics, as the “Other” group is small (4%) and heterogeneous.
