Table 3.

PCAs of NIHTB-CB tests

	PCA 1a (including RAVLT-DR, N = 197)			PCA 2a (excluding RAVLT-DR, N = 198)
	Component			Component
	1	2	3	1	2
	Memory (MEMNIH)	Executive function (EFNIH)	Crystallized intelligence (CINIH)	Executive function/working memory (EF/WMNIH)	Crystallized intelligence (CINIH)
RAVLT Trial 2	0.886			0.823
RAVLT-DR	0.853
RAVLT Trial 3	0.852			0.838
RAVLT Trial 1	0.818			0.711
Flanker		0.897		0.842
DCCS		0.874		0.84
Pattern Comparison		0.833		0.867
ODS		0.741		0.876
Oral Reading Recognition			0.89		0.891
Picture vocabulary			0.702		0.714
% Explained variance	35%	33%	15%	55%	17%
Total % explained variance	83%			72%

Abbreviations: NIHTB-CB, NIH Toolbox Cognition Battery; PCA, principal component analysis; RAVLT, Rey Auditory Verbal Learning Test immediate recall; RAVLT-DR, Rey Auditory Verbal Learning Task delayed recall; Flanker, Flanker Inhibitory Control/Attention; DCCS, Dimensional Change Card Sort; Pattern Comparison, Pattern Comparison Processing Speed; ODS, Oral Digit Symbol.

NOTE. PCA was conducted using varimax with Kaiser Normalization. Factors with eigenvalues greater than 1, with a maximum iteration of 25, were extracted—factor loadings shown after orthogonal rotation.

NOTE. PCA 1a rotation converged in 5 iterations. The Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy = 0.90.

NOTE. PCA 2a rotation converged in 3 iterations. KMO = 0.89.