Invariance of a two-factor model of Social Dominance Orientation across gender

This research examined the measurement and structural invariance of the 16-item Social Dominance Orientation (SDO) scale across gender. The Social Dominance Theory (SDT) invariance hypothesis proposes that men are higher than women in SDO. Tests of this hypothesis have compared summary scores with t-tests, but there is no psychometric work of measurement invariance across gender, which makes interpretation of t-test comparisons problematic. Some research suggests the scale captures two distinct factors: support for group-based dominance (GBD) and general opposition to equality (OEQ). However, gender differences in GBD and OEQ have mixed findings. Results replicated the two-factor structure. Multiple-group CFA indicated that loadings, intercepts, factor variances, and factor covariance are equivalent across gender. Males demonstrated higher latent means of GBD and OEQ, supporting the SDT invariance hypothesis.