ND was assessed using items from the Fagerstrom Test for Nicotine Dependence (FTND) (Heatherton et al. 1991). FTND score was further categorized into five levels of dependence: scores of 0–2 are grouped as ‘very low’; 3–4 as ‘low’; 5 as ‘medium’; 6–7 as ‘high’; and 8–10 as ‘very high’. A subset of items from the FTND was also asked of snus users: (i) latency to first snus; (ii) which snus would you most hate to give up?; (iii) quantity snused; and (iv) do you snus more in the morning? To maintain consistence with the cigarette-oriented FTND, we converted snus consumption (originally reported in terms of snus boxes per week) to the comparable amount of cigarettes per day using Fagerstrom (2005) as a guide. Due to having fewer questions on this modified FTND scale, we grouped users into only four categories of dependence. We will refer to measures of ND derived from questions regarding cigarette use as NDC, and those derived from questions regarding snus use as NDS.
