We report analyses of the full intensively studied sample to retain statistical power. Based on our sensitivity analyses, the type of sampling (random versus non-random) did not attenuate estimates of the associations between tobacco use and SRB variables. The intensively studied sample analyzed for this study included 1330 individual twins (626 males, 704 females) who provided sufficient data on tobacco use and SRB. Non-respondents at follow-up did not significantly differ from the respondents at baseline in terms of depression status, sex, age or tobacco use status. However, due to missing values in potential confounders, the final sample sizes varied in the multiple adjusted analyses from 1266 (592 males, 674 females) to 1269 (594 males, 675 females).
