Participants carried a Cassiopeia Pocket PC PDA (Casio Model E-125, Casio Computer Co., Japan). The Cassiopeia Pocket PC has a touch-sensitive color screen and a silo for a stylus. Native pocket PC programming (calendar, date book, address book, etc.) was blocked, and a specialized EMA program was put in its place. Participants were instructed to access the PDA before smoking each cigarette throughout the day and night, and to answer questions if they appeared on the screen. They were also instructed to respond to PDA alarms that would occur periodically throughout the day and to answer any questions that appeared on the PDA screen. Each day was tailored to the participant (based on their typical wake-up and bed time) by dividing the day into three epochs roughly corresponding to morning, afternoon, and evening. The program was designed to randomly obtain one of each type of assessment (before, after, random) once during each epoch to gain a representative sample of smoking throughout the day.
