Viability of a MSQOL-54 general health-related quality of life score using bifactor model

Table 2 Model description and fit statistics of confirmatory factor analysis

Model type	DF	AIC	BIC	RMSEA	CFI	SRMR
Two second-order factors ^a	1260	1,711,214	1,712,270	0.055	0.888	0.064
Single second-order factor ^b	1262	1,711,735	1,712,778	0.056	0.884	0.068
Bifactor 1^c	1223	[1710635]	[1711920]	[0.055]	[0.892]	[0.062]
Bifactor 2^d	1225	1,710,637	1,711,910	0.055	0.892	0.062

AIC, Akaike information criterion; BIC, Bayesian information criterion; RMSEA, root mean square error of approximation; CFI, comparative fit index; DF, Error degree of freedom; SRMR, standardized root mean square residual
^a 12 first-order factors and two second-order factors; the correlation between the two second-order factors was 0.87
^b 12 first-order factors and one second-order factor
^c 11 group factors and one general factor; residual of overall quality of life (QOL) subscale items (items 53 and 54) were allowed to correlate. Solution not admissible as item 20 showed a negative variance
^d 10 group factors and one general factor; items of the social function subscale (20, 33, 51) loaded onto the general factor only, and residual of the overall QOL subscale items (53, 54), and the residual of items 20 and 33 of the social function subscale were allowed to correlate

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