A CONTINUOUS-TIME MARKOV CHAIN APPROACH ANALYZING THE STAGES OF CHANGE CONSTRUCT FROM A HEALTH PROMOTION INTERVENTION.

The Transtheoretical Model of behavior change is often used in longitudinal research of health-related outcomes. This model includes a construct called stage of change, which is a hypothesized concept of progression for individuals trying to modify their behavior. Project HOME (Healthy Outlook on the Mammography Experience), a population-based randomized group intervention trial sought to identify factors associated with subject changes in stage, from precontemplation to contemplation and from contemplation to action. The aims of this paper are to extend Li and Chan's Markov model approach to handle multiple covariates that include both continuous and binary variables. An empirical study was conducted to evaluate the accuracy of the estimators. The model was then applied to the Project HOME data. Specifically, we present a continuous-time Markov chain approach to examine covariates and their effect on the dynamics of the changes in stage. This model can be used by researchers to more fully describe transitions in data.