Drinking data were extracted from all phases at which alcohol consumption questions were incorporated: phases 1 (1985–88), 2 (1989–90), 3 (1991–93), 5 (1997–99), 7 (2003–04), 9 (2007–09) and 11 (2012–13). Participants were asked to report the frequency with which they consumed alcohol during the year preceding interview. This information was used to derive a baseline frequency variable: ‘daily or almost daily’ and ‘not daily or almost daily’.
