Questionnaires included items inquiring whether the individual smoked cigarettes, pipes, or cigars and, if so, how many per day. Participants were considered daily smokers in a year if they indicated smoking any type of tobacco on a daily basis. Non-smokers included participants who indicated no use of any type of tobacco at that assessment and those indicating that their use of tobacco was less than daily. Quitting daily smoking was defined as reporting no daily use of tobacco following one or more assessments where daily smoking was reported.
