Cigarette use was assessed using three items indexing frequency and quantity of use: (i) ‘Have you ever smoked regularly, that is, at least 1 cigarette every day for 30 days?’ Response options were 1 “Yes” and 0 “No”, (ii) ‘During the past 30 days, on how many days did you smoke cigarettes?’ Response options ranged from 0 “No days” to 30 “thirty days”, (iii) During the past 30 days, on the days you smoked, how many cigarettes did you smoke each day?’ Items were standardized before they were combined to provide an overall index of cigarette use. The measure had good internal consistency at each time point (Time 1, α = .83; Time 2, α = .85).
