are comparatively common among people with NAP. Exclusion of NAP, then, presumably led to an overestimation of the net effects of smoking. Fourth, although control data on history of pre-existing mental disorders and suicidality were gathered prospectively in our two-wave panel survey, the measures in each survey were based on retrospective reports. For example, the aspect of baseline tobacco use most strongly predictive of later SROs was early-onset nicotine dependence, a measure that required respondents to provide retrospective reports in the baseline survey about their age when they first experienced symptoms of dependence. Similarly, the outcome measures required respondents to make retrospective reports about the occurrence of SROs in the decade since the baseline survey. Systematic recall errors in these reports could have introduced bias into our estimates of predictive associations. Some indication that retrospective recall of smoking history is likely to be unbiased comes from our investigation of the fact that the detailed baseline assessment of smoking history was obtained only from the respondents in the tobacco supplement. Our finding that the associations of baseline smoking with subsequent SROs were equivalent in magnitude whether smoking was assessment prospectively or retrospectively argues against the existence of retrospective recall bias at
