At age 12, a dichotomous variable on having ever tried smoking was used; with “Yes” responses coded as 1 and “No” responses as 0. Based on several questions on smoking initiation and current smoking habits, any current smoking and current daily smoking at ages 14, 17 and in young adulthood were studied. These smoking behaviors were indexed by two dichotomous variables, one for any current smoking and one for daily smoking, for which “Yes” responses were coded as 1 and “No” responses as 0.
