Preliminary validation of the insomnia severity index in Danish outpatients with a medical condition

Journal of Patient-Reported Outcomes

Table 2 Fit indices of confirmatory factor analyses in different Insomnia Severity Index factor models (n = 249)

Model	Chi²	p-value	RMSEA	CFI	TLI	SRMR	AIC	BIC	p-value^*
Threshold for fit indices	None	> 0.05	< 0.08	≥0.90	≥0.95	< 0.08	Lowest value	Lowest value	< 0.05
Model 1. One factor: All 7 items	87.030	< 0.001	0.145	0.931	0.896	0.048	4285.162	4359.028	ref
Model 2. Two factors: Subscale 1: 1, 2, 3, 4 Subscale 2: 5, 6, 7	40.577	< 0.001	0.092	0.974	0.958	0.033	4240.709	4318.093	1.0
Model 3. Two factors: Subscale 1: 1, 2, 3 Subscale 2: 4, 5, 6, 7	67.746	< 0.001	0.130	0.948	0.916	0.042	4267.877	4345.261	1.0
Model 4. Three factors: Subscale 1: 1, 2, 3 Subscale 2: 1, 4, 7 Subscale 3: 5, 6, 7	26.497	0.002	0.089	0.983	0.961	0.025	4234.629	4326.083	1.0

Bold text for the best fitted value for the indices
RMSEA Root Mean Square Error of Approximation, CFI Comparative Fit Index, TLI Tucker–Lewis fit Index, SRMR Standardized Root Mean Square Residual, AIC Akaike’s Information Criterion, BIC Bayesian Information Criterion
^*Likelihood ratio test