Establishing validity and reliability of an instrument using the theory of planned behavior to predict middle school student obesity-related actions

Background: Childhood obesity is of concern to many health professionals, parents, teachers, and school administrators because of the negative impact on the child's physical, psychological, and behavioral health. Lack of structured monitoring and evaluation has hindered the development of an evidence base to disseminate best practices in childhood obesity prevention. Purpose: The purpose of this study was to develop a valid and reliable instrument which affirmed the constructs of the Theory of Planned Behavior in relation to nutrition and physical activity behaviors related to childhood obesity. Methods: A convenience sample of 242 students participated in the validation of the 129-item instrument, which was administered during class time, and read to students to increase response rate. Results: Confirmatory factor analysis established instrument validity, with one factor present for each behavior, and factor loadings greater than 0.32. Reliability and test-retest coefficients achieved apriori criteria of 0.70. Discussion: Truly learning how to gauge nutrition and physical activity levels in children and adolescents has proved to be difficult, yet it is imperative to understand the relationship of the proposed potentially modifiable behaviors and childhood obesity.