Assessing how people change.

Traditional assessments of behavior change relied on discrete measures based on assumptions that changes occur quickly, dichotomously, and without relapse. People were expected to shift dramatically from smokers to nonsmokers or from unhealthy to healthy lifestyles. A stage model of change has greater potential to assess the dynamics of change with some people progressing linearly from contemplation to maintenance, others relapsing back to contemplation, and others remaining in a stage like contemplation for long periods. Stage measures provide differential predictions for the amount of progress people in different stages will make after treatment. Assessing processes of change that people apply to progress from one stage to the next can also help to explain the dynamics of behavior change.