Table 2.

Fit statistics of two-parameter IRT models within each study

Study	No. items	RMSEA	CFI	SRMR	Bifactor
ADSPlus	12	0.059	0.927	0.1	No
ACT	20	0.043	0.868	0.111	Yes
ADAMS	18	0.048	0.913	0.11	Yes
ALZQOL	25	0.033	0.952	0.123	Yes
COPE	19	0.037	0.925	0.103	Yes
NACC	23	0.069	0.753	0.123	Yes
REACH II	17	0.056	0.85	0.103	Yes
TAP	16	0	1	0.118	Yes