Respondents were asked how often in the month before the interview they had consumed each of the following substances: tobacco, alcohol, alcohol to the point of drunkenness, and cannabis (0 = never, 1 = 1–3 times a month, 2 = 1–2 times a week, 3 = 3–6 times a week, 4 = daily). Due to very low response frequencies (see Table 1), daily alcohol use was combined with alcohol use 3–6 times a week. Also, for drunkenness higher categories were collapsed to 1–2 times a week or more often. Variables were treated as binary or ordinal.
