The age of drinking onset was ascertained by asking respondents how old they were when they first started drinking, not counting small tastes or sips of alcohol. Drinking onset data were collected from respondents who were classified as current drinkers (i.e., who had consumed at least 12 drinks in the past 12 months) and former drinkers (i.e., who had consumed at least 12 drinks in any 1 year of their lives but not during the year preceding the interview). The test-retest reliability of the drinking onset variable was good, with a kappa of 0.72 (Grant et al. 1995).
