An analysis of the predictive power of the transtheoretical model of behavior change applied to dietary fat intake

Julie A Wright, University of Rhode Island


The present research was designed to advance the theory and science of health behavior change by evaluating one of the most commonly used behavior change theories, the Transtheoretical Model (TTM). Two criteria were selected for evaluation, empirical adequacy (predictive power) and generalizability of the TTM to dietary fat intake. Predictive power was evaluated by testing evidence-based a priori predictions. Generalizability was evaluated by testing a priori predictions founded on smoking data and tested on diet data. Longitudinal data from a large scale randomized control trial on adults recruited from primary care practices were used to test a priori predictions of effect size based on the TTM applied to dietary fat intake. Two sets of predictions were made for diet; (a) one set was based on effect sizes found in cross-sectional and longitudinal smoking data; and (b) one set was generated from cross-sectional diet data from separate samples of adults. These predictions were examined in three studies: (a) Study 1 examined those in Precontemplation at baseline, (b) Study 2 examined those in Contemplation at baseline, and (c) Study 3 examined those in Preparation at baseline. After predictions were made, quantitative analyses determined whether the predictions were corroborated. ^ The research found that the TTM predicted behavior change in dietary fat intake with a moderate to high degree of accuracy. Additionally, 77–85% of the smoking based predictions generalized to diet data indicating a moderate degree of generalizability from smoking to diet. Based on the results, new hypotheses were generated for the next step of theory testing. Future studies, such as the present, should continue to evaluate the TTM to provide more data that can be added to the nomological net that defines its validity. ^

Subject Area

Psychology, Behavioral|Health Sciences, Nutrition|Psychology, Experimental

Recommended Citation

Julie A Wright, "An analysis of the predictive power of the transtheoretical model of behavior change applied to dietary fat intake" (2002). Dissertations and Master's Theses (Campus Access). Paper AAI3053128.