Table 2.

Results of invariance testing.

Model	Invariance testing strategy	Parameters estimated			df	χ2	χ2/df ratio	AGFI	TLI	RMSEA
0. 1-factor independence model	Combined groups: 1 set of parameters estimated across the groups	18 total, across groups (15 betas, 3 latent variances)			153	2143.73, p < .001	14.01	.62	.00	.14
1. 3-factor constrained model	Combined groups: 1 set of parameters estimated across the groups	39 total, across groups (15 betas, 18-item variances, 3 latent variances, 3 latent covariances)			132	596.18, p <.001	4.52	.877	.730	.071
2. 3-factor unconstrained model	Test of configural invariance separate groups: 2 sets of parameters estimated separately within each group	78 total: all within groups	Group 1 (39): 15 betas, 18-item variances, 3 latent variances, 3 latent covariances	Group 2 (39): 15 betas, 18-item variances, 3 latent variances, 3 latent covariances	264	730.12, p < .001	2.77	.896	.729	.051
3. Measurement weights model	Test of metric invariance separate groups: constrains the betas to be equal across groups, estimates other parameters freely within groups	63 total: 15 betas across groups	Group 1 (24): 18-item variances, 3 latent variances, 3 covariances	Group 2 (24): 18-item variances, 3 latent variances, 3 covariances	279	753.75, p < .001	2.70	.861	.739	.050
χ2 difference test, compared to unconstrained model							χ2 (15) = 23.6, p = .07	.04	.10	−.001
4. Structural covariance model	Test of construct variance/covariance invariance constrain the latent variable covariances only	75 total, 3 latent covariances across groups	Group 1: 18-item variances, 15 betas 3 latent variances	Group 2: 18-item variances, 15 betas 3 latent variances	267	747.69	2.80	.856	.723	.051
χ2 difference test, compared to unconstrained model							χ2(3) = 17.57, p < .001	.00	−.000	.001

betas: regression coefficients; AGFI: adjusted goodness of fit index; RMSEA: root mean square error of approximation; TLI: Tucker–Lewis index.