Stage of change transitions and processes of change, decisional balance, and self-efficacy in smokers: a transtheoretical model validation using longitudinal data.

Interactions were examined between stage of change transitions and intraindividual increases or decreases in the processes of change, pros and cons of smoking, and situational temptations longitudinally. A total of 786 ever smokers was assessed 2 times, 6 months apart, with respect to the transtheoretical model (TTM) constructs. Two significant discriminant functions within initial precontemplators and 1 significant function within initial contemplators were found. Ten out of 15 TTM variables contributed to at least 1 function. The functions mainly distinguished between preabstinence (precontemplation, contemplation, or preparation) and abstinence (action or maintenance) stages of change, that is, between current and former smokers. This is one of the few studies providing a longitudinal validation of the postulates of the TTM.