Table 1
Descriptive statistics: continuous variables (n = 3575)
Mean
SD
Age (years)
40.7
10.0
Age started smoking (years)
16.8
3.8
Fagerström test for nicotine dependence (score)
4.7
1.3
Blood nicotine (ng/ml)
15.1
9.0
Blood cotinine (ng/ml)
270.5
112.5