A bifactor model supports unidimensionality of the International Knee Documentation Committee Subjective Knee Form in young active patients with anterior cruciate ligament tears: a retrospective analysis of a randomized controlled trial

Table 3 Model structures tested the International Knee Documentation Committee Subjective Knee Form (IKDC) in young patients with anterior cruciate ligament tears using confirmatory factor analysis

	Model Structure Tested	χ² (df)	CFI	TLI	RMSEA (90% CI)	SRMR	Covariances < 0.85?	Loadings > 0.3?
1	One-factor	1762.04 (135)	0.673	0.629	0.141 (0.135 to 0.147)	0.091	N/A	Yes
2	Two-factor	982.65 (134)	0.829	0.805	0.102 (0.096 to 0.108)	0.072	Yes	Yes
3	Four-factor	450.72 (129)	0.935	0.923	0.064 (0.058 to 0.071)	0.055	Yes	Yes
4	Bifactor	291.78 (117)	0.965	0.954	0.050 (0.043 to 0.057)	0.047	Yes	Yes^a

Acceptable values: CFI and TLI > 0.9, RMSEA and SRMR < 0.08, all factor covariances < 0.85, and all factor loadings > 0.3
All analyses were run with Mplus software using a continuous approach and maximum likelihood estimation
^aIncludes only loadings onto the general factor

ISSN: 1477-7525