Table 1. Fits of the main SEMs tested.

Model	χ2	df	RMSEA	CFI	SB	AIC
Single-factor (A), e.g., Berry et al.37	645	27	0.270	0.722	1.080	2838
Two-factor (B), e.g., Squire38	424	26	0.220	0.821	1.032	2580
Two-factor (C), e.g., Gardiner et al.39	340	26	0.196	0.859	1.001	2483
Two-factor (D), e.g., Yonelinas24	324	23	0.211	0.855	0.940	2472
Three-factor (E)	78	24	0.084	0.976	0.946	2220
Three Factor with Age	80	30	0.072	0.980	0.946	2928
Three Factor with Age & Edu	94	36	0.071	0.977	0.953	3778
Three Factor with Age, Edu & gF	214	78	0.074	0.957	0.977	6725
Three Factor with GM and WM ROIs*	118	72	0.046	0.981	0.982	7815
Three Factor with GM constrained*	142	78	0.052	0.974	0.983	7828
Three Factor with WM constrained*	135	78	0.049	0.977	0.984	7821
Three Factor with GM, WM and Age*	139	85	0.046	0.979	0.980	8282
Three Factor with WM, Age, GM-nulled*	159	94	0.048	0.974	0.979	8283
Three Factor with GM, Age, WM-nulled*	149	94	0.044	0.972	0.985	8273

The SEMs are grouped according to those fitting the same data (same observed variables), since one cannot compare all model fit indices across fits to different data. Edu = Education Level; gF = Fluid Intelligence; GM = Gray Matter (Volume); WM = White Matter (Index). For fit measures, see Methods (df = degrees of freedom left in data). *=These models additionally contained Education and TIV (affecting all memory factors). Note that the χ² reported is the Satorra-Bentler scaled χ², with the scaling factor reported as SB.