Date of Award


Degree Type


Degree Name

Master of Arts in Psychology



First Advisor

Joseph S. Rossi


The transtheoretical model of health behavior related-change indicates that people who successfully change a problem behavior move through a series of stages of motivational readiness in their attempts to change. This model has been successfully applied to a wide range of health-related behaviors, and in this study was applied to the area of weight control. The goals of this study were a thorough psychometric examination of a key transtheoretical model construct known as the processes of change (POC), the different strategies people use to change their behavior while progressing from one stage of change to the next, and the development of a robust POC measure for weight control.

Questionnaires from 724 participants recruited as part of a larger naturalistic study on smoking behavior were used to ascertain the validity of the process of change construct for weight control. In this questionnaire, 60 items concerned strategies participants used to control or lose weight. Measurement development followed a split-half cross-validation procedure. On the first half of the sample (n=3 18), principal components analysis revealed moderate deviation from theoretical expectations. Several rounds of reevaluation of theoretical fit, using structural equation models (SEM), and concomitant item evaluation, using Cronbach 's coefficient Alpha and SEM modification indices to inform decision making, resulted in a 34 item measure reflecting the 12 processes of change.

After arriving at a more parsimonious measure in the first half of analysis, confirmatory analysis on the second half of the sample (n = 317) was undertaken using structural equation modeling in order to confirm the final solution and refine the theoretical model. The final structural model that fit best was a 12 correlated factors model. Also, two hierarchical factors (experiential and behavioral) were found. These results are similar to findings for POC models established for other problem behaviors. Construct validity of the revised instrument was established via a series of stage by process analyses which revealed that particular weight control POC are utilized at specific stages of change, in line with theoretical expectations. These analyses also indicated that this instrument is applicable for individuals in all stages of change for weight control.

Thus, this study accomplished two goals: development of a shortened process of change instrument for weight control that meets rigorous psychometric standards, and theoretical refinement of the process of change model for this important content area. Given that, this study has positive implications for both professional and public health interventions on weight control. Since particular weight control POC are utilized at specific stages of change, interventions can be developed for individuals in all stages of change for weight control. The revised POC instrument can identify the strategies individuals are currently using in their efforts to control their weight, and when used in conjunction with expert system technology, can be used to give feedback to help individuals move efficiently through the stages. Such interventions employing the POC for weight control can thus maximize efforts towards successful weight control.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.