For the present study, we limit our sample to 33,869 respondents (18539 from NLAES and 15,330 from NESARC) who were born in the United States between 1948 and 1970. For comparisons across waves, subjects were divided into cohorts born between 1948 and 1955 (who were reaching age 18 in the era when minimum purchase ages were being lowered), and cohorts born between 1956 and 1970 (who were coming of age in the era when minimum purchase ages were being raised). In our age-restricted analysis, the sample was further limited to the 18,136 subjects who had reached the ages of 18, 19, or 20 within two years of an MLDA law change affecting alcohol purchase by 20 year olds.
