Methods
Data
The data came from the Finnish Drinking Habits Survey, a general population survey of Finns aged 15–69 years. The sample was drawn from population census using simple random sampling excluding A ̊land Islands (0.5% of the population), the homeless and the institutionalized (1.5%). The survey was carried out in 2008 by Statistics Finland as face-to-face interviews. Response rate was 74%. Weights calculated by post-stratification for sex, age and geo- graphical region were used to restore the population representation. The study protocol was approved by the ethical committees of the National Research and Development Center for Welfare and Health STAKES (later THL) and Statistics Finland.