Three subsets of the sample were used, described in Table 3. The initial analysis was done only with “Current frequent smokers” which included individuals reporting having used tobacco at least 180 days (almost every day) in the six months prior to the interview. This is more stringent (restricting the sample to current smokers) but similar to the inclusion criteria used by Bierut et al of having smoked at least 100 cigarettes (Bierut et al, 2007). Secondary analyses were done with 1) sets of “smokers” who were individuals who reported having used tobacco almost every day for at least a month at some point in their life, and 2) the entire sample of 1051 individuals.
