was calculated by summing the reports of DSM-IV smoking withdrawal symptoms. Specifically, subjects were asked about problems that they might have had when they stopped smoking or smoked less tobacco than usual. They answered “yes” or “no” to each of nine questions: 1) Were you irritable, angry, or frustrated? 2) Were you nervous or anxious? 3) Were you restless? 4) Did you have trouble concentrating? 5) Did your heart slow down? 6) Did you feel down or depressed? 7) Did you have such a strong desire for cigarettes that you couldn't think of anything else? 8) Did your appetite increase or did you gain weight? 9) Did you have trouble sleeping? In a separate stage of this assessment, subjects were asked whether symptoms 1-7 lasted for at least 24 hours. For each assessment, only subjects that reported at least one withdrawal symptom were included in the analysis.
