The pattern of alcohol onset in the survival curve (Figure 2) illustrates close approximations of the rates obtained by large-scale epidemiological studies such as Monitoring the Future (MTF) (Johnston et al., 2008). The mean age of alcohol onset for those who reported drinking in the current sample was ~16 years which roughly corresponds to the 58% lifetime alcohol use rate reported for 10th graders in the 2008 MTF report. In addition, the probability for alcohol onset increased with age, and only one subject in the 18+ age range denied ever trying alcohol. In viewing these results shown in Figure 2, it is important to remember that DTSA includes offspring who have not yet passed through the full age of risk for drinking onset. This allows us to examine how predictors relate to drinking onset at each age for all subjects regardless of their lifetime alcohol use. However, the inclusion of these younger respondents impacts the slope of the survival curve to plateau at about age 21 across time.
