As in other studies, we found that exposure to a lower legal purchase age did predict earlier self-reported ages at onset of regular drinking. In a logistic regression controlling for sex, ethnicity, age group, study, parental alcohol problems and state and birth year fixed effects, MLDA exposure based on current state of residence was not a significant predictor of self-reported onset of drinking before age 16 (OR .1.02, 95% ci .92 to 1.14, p = .70), but in multinomial logistic regressions controlling for the same covariates, (with onset before age 16 as the omitted group) we found that respondents exposed to a lower MLDA were significantly more likely to have started drinking at age 18 (OR 1.16, 95% ci 1.00, 1.35, p = .05), and less likely to have started drinking at age 21 (OR .66, 95% c.i. 54 to .81, p <.0001), However, an earlier legal purchase age had no significant effect on the likelihood of onset of drinking at 16 or 17 (OR 1.03, 95% ci .91, 1.16, p=.68), age 19 or 20 (OR .88, 95% ci .75
