Table 3.

Measurement invariance for the simplified Japanese version of the Athens Insomnia Scale (AIS‐SJ) across participants’ characteristics (n = 50 547)

	Chi‐squared	df	RMSEA	ΔRMSEA	CFI	ΔCFI
Gender: men = 22,878 versus women = 27,669
Model 1: configural invariance	3,616	38	0.061	–	0.984	–
Model 2: strict invariance		42	0.066	0.005	0.979	−0.005
Age: younger = 35,960 versus older = 14,587
Model 1: configural invariance	3536	38	0.061	–	0.985	–
Model 2: strict invariance	6619	42	0.079	0.018	0.972	−0.013
History of mental illness: experience with = 2,676 versus none = 46,513
Model 1: configural invariance	3720	38	0.063	–	0.981	–
Model 2: strict invariance	3893	42	0.061	−0.002	0.980	−0.001

RMSEA, root mean square error of approximation; CFI, comparative fit index.