We defined five age categories: 12 to 14 years old, 15 to 17 years old, 18 to 20 years old, 21 to 23 years old, and a reference category comprising 24 to 34 years old of both sexes. The last group was chosen to represent young adults who are several years past the legal drinking age, both before and after the transition to a uniform MLDA of 21. The upper limit for the 24–34 year age range was defined based on age category definitions in recent NSDUH survey public use data files, which do not specify exact year of birth. Race/ethnicity was coded as White, Black, Hispanic, or Other. Individuals indicating Hispanic ethnicity were considered to be “Hispanic” regardless of race. Individuals indicating more than one race, as well as non-Caucasian and non-African-American races were coded as “Other”.
