Table 2.

Model-fit results of confirmatory factor analysis (CFA) of extended item bank (51 items), final item bank (28 items) and short-form 8b (8 items) of the PROMIS Depression Item Bank using WLSMV^a,b

Model	χ2 value	df	p	RMSEA [90% CI]	CFI	TLI
Unidimensional model with 51 items	5729.6	1224	<.001	0.070 [0.068; 0.072]	0.953	0.951
Unidimensional model with 28 items	1473.27	350	<.001	0.065 [0.062; 0.069]	0.983	0.982
Unidimensional model with 8 items	177.71	20	<.001	0.101 [0.088; 0.115]	0.995	0.992

^aWLSMV: robust weighted least squares

^bSample size for the models with 51, 28 and 8 items, respectively, was N = 753