The frequency or volume criterion was constructed as a function of two variables measured in the NESARC. The first was a cannabis use frequency measure during the 12 months preceding the interview with the following response categories: every day; nearly every day; 3 to 4 times a week; 1to 2 times a week; 2 to 3 times a month; once a month; 7 to 11 times a year; 3 to 6 times a year; 2 times a year; and once a year.
