Do Items That Measure Self-Perceived Physical Appearance Function Differentially Across Gender Groups? An Application of the MACS Model

Abstract

The aims of this study were to investigate whether the 6 items of the Physical Appearance Scale (Marsh, Richards, Johnson, Roche, & Tremayne, 1994) show differential item functioning (DIF) across gender groups of adolescents, and to show how this can be done using the multigroup mean and covariance structure (MG-MACS) analysis model. Two samples composed of 402 boys and 445 girls were analyzed. Two DIF items were detected. One of them showed uniform DIF in the unexpected direction, whereas the other showed nonuniform DIF in the expected direction. The practical significance of the DIF detected was trivial. Thus, we concluded that the differences between girls' and boys' average scores on the analyzed scale reflect valid differences on the latent trait.