The average number of cigarettes smoked in a day among current and former smokers. Studies with binned responses used their existing bins. Studies that recorded an integer value binned responses into one of four categories: 1=1–10, 2=11–20, 3=21–30, 4=31 or more. Anyone reporting 0 cigarettes per day was coded as missing. This phenotype is a component of commonly used measures of nicotine dependence such as the Fagerstrom Test for Nicotine Dependence.
