Validity, reliability, and invariance of the Situational Motivation Scale (SIMS) across diverse physical activity contexts

This research assessed the reliability, presence of a proposed simplex pattern (construct validity), factorial validity, and multisample invariance of the Situational Motivation Scale (SIMS; Guay, Vallerand, & Blanchard, 2000). In Study 1, data were collected from three physical activity samples. After establishing internal consistencies for all scales, bivariate and interfactor correlations were calculated and the results supported a simplex pattern across samples. The SIMS factorial validity across the three samples was tested via confirmatory factor analysis. Based on modification indices and theoretical justification, the SIMS was reduced to a 14-item model and the multisample invariance of this solution was examined. Results supported partial invariance. In Study 2, a total of 1,008 female PE students responded to the SIMS under two experimental conditions. Internal consistency and the assumed simplex pattern was again supported. Finally, the results of multisample CFA were consistent with the proposed post hoc model respecifications suggested in Study 1, supporting partial invariance.