Strong and weak principles for progressing from precontemplation to action on the basis of twelve problem behaviors.

Two principles for progressing from the precontemplation stage of change to the action stage were discovered. The strong principle states that progression from precontemplation to action is a function of approximately a 1 standard deviation increase in the pros of a health behavior change. The weak principle states that progression from precontemplation to action is a function of approximately a 1/2 standard deviation decrease in the cons of a health behavior change. In Study 1, these principles were derived from cross-sectional data on 12 problem behaviors relating the pros and cons of changing to the stages of change. In Study 2, these principles were validated on cross-sectional data from an independent sample of 1,466 smokers. Discussion focuses on the implications of these principles for individual psychology and public health policy.