Non-treatment-seeking smokers (N=72) were recruited from the Houston metropolitan area through newspaper advertisements. Participants were an average age of 43.2 years (SD=10.0), were 53% female, smoked 21.8 cigarettes per day (SD=9.7), had Fagerström Nicotine Tolerance scores of 5.5 (SD=1.8), had a baseline expired carbon monoxide level of 23.7 (SD=9.5), were 54% Black, 38% White, and 8% Asian, Hispanic, or other. Participants were originally enrolled in a larger study, which included four laboratory sessions scheduled approximately 3 days apart. Participants carried personal digital assistants (PDAs) an average of 12.5 days (SD=4.3) on the days between laboratory sessions. Because of the demands of the main study, the number of days each participant carried the PDA varied because of rescheduling, missed laboratory sessions, or study dropouts.
