Self-efficacy as an intermediate outcome variable in the transtheoretical model: Validation of a measurement model for applications to dietary fat reduction

Bandura's self-efficacy construct is one of the elements examined in the transtheoretical model. Applied to dietary fat reduction, self-efficacy is conceptualized as confidence in the ability to avoid consuming high-fat foods in three situations (positive/social, negative/affective, and difficult/ inconvenient). The validity of a 12-item situational self-efficacy scale designed to measure confidence for dietary fat reduction in a U.S. population was investigated with a random sample of 491 adult women living in the Guelph, Ontario area. Participants were recruited by telephone and completed a mailed, self-administered questionnaire. Principal components analysis revealed a three-factor structure accounting for 74% of the variance in self-efficacy. Loadings on the three factors ranged from .62 to .96. The three factors demonstrated high internal consistency (alpha) coefficients, ranging from .83 to .95. Confirmatory factor analysis demonstrated excellent model fit (comparative fit index = .96) with all parameters significant. Self-efficacy scale scores were significantly higher among subjects assigned to action and maintenance than among those assigned to precontemplation, contemplation, and preparation, providing evidence of construct validity. This scale, developed with an American population, demonstrates validity when applied to Canadian adult women.