. Author manuscript; available in PMC: 2017 Feb 22.

Published in final edited form as: J Clin Exp Neuropsychol. 2016 Feb 22;38(5):534–550. doi: 10.1080/13803395.2015.1136598

Table 4.

Multilevel models of 6 year cognitive change as a function of time in study, age, education & RT inconsistency for CRT and BRT.

CRT Models	Digit Symbol		Letter Series		Word Recall		Verbal Fluency		Vocabulary
Fixed Effects	Estimate	SE	Estimate	SE	Estimate	SE	Estimate	SE	Estimate	SE
Intercept (γ₀₀)	37.54^***	0.91	7.04^***	0.44	14.79^***	0.42	10.72^***	0.55	28.01^***	0.47
CRT ISD (γ₀₃)	−1.60^***	0.20	−.68^***	0.10	−0.56^***	0.09	−0.71^***	0.12	−0.47^***	0.11
Slope (γ₁₀)	0.36	0.22	0.00	0.07	0.08	0.10	−0.02	0.13	−0.02	0.06
CRT ISD (γ₁₃)	−.02	0.06	0.01	0.02	−0.06^*	0.27	−0.01	0.03	−0.04^*	0.02

Random Effects
Intercept (u_0i)	42.01^***	4.69	11.42^***	1.11	9.14^***	1.00	15.30^***	1.73	14.04^***	1.26
Slope (u_1i)	0.64^**	0.24	0.01	0.03	0.19^***	0.05	0.16^*	0.08	0.02^**	0.01
Covariance	1.80^*	0.79	0.08	0.13	0.33	0.17	0.23	0.29	−0.16	0.12

Residual (e_ij)	24.25^***	1.27	3.49^***	0.18	4.87^***	0.25	9.25	0.48	2.39^***	0.12

BRT Models	Digit Symbol		Letter Series		Word Recall		Verbal Fluency		Vocabulary
Fixed Effects	Estimate	SE	Estimate	SE	Estimate	SE	Estimate	SE	Estimate	SE
Intercept (γ₀₀)	38.40^***	0.88	7.54^***	0.40	15.01^***	0.43	11.09^***	0.55	28.27^***	0.47
BRT ISD (γ₀₃)	−1.59^***	0.17	−0.88^***	0.07	−−0.44^***	0.08	−0.68^***	0.10	−0.49^***	0.09
Slope (γ₁₀)	0.37	0.22	−0.01	0.07	0.11	0.10	−0.01	0.13	−0.00	0.06
BRT ISD (γ₁₃)	−.02	0.04	0.01	0.01	−0.05^*	0.02	−0.01	0.02	−0.01	0.01

Random Effects
Intercept (u_0i)	37.71^***	4.33	8.58^***	0.88	9.32^***	1.01	14.63^***	1.67	13.52^***	1.22
Slope (u_1i)	0.64^**	0.24	0.01	0.03	0.18^***	0.05	0.16^*	0.08	0.02^**	0.01
Covariance	1.78^*	0.76	0.13	0.11	0.33	0.17	0.21	0.28	−0.13	0.11

Residual (e_ij)	24.24^***	1.26	3.49^***	0.18	4.87^***	0.25	9.25	0.48	2.40^***	0.12

NOTE: For all multilevel analyses, Age was centered at 75 years and Education was categorized as > or ≤ 12 years of formal education.

γ₀₀ = average cognitive performance for a 75 year-old individual with ≤12 years of education at Year-1; γ₀₃ = average difference in cognitive performance for a 1-unit increase in variability (CRT ISD, BRT ISD) at year 1; γ₁₀ = average amount of cognitive change per year increase of being in the study; γ₁₃ = average difference in rate of change associated with a 1-unit increase in time in study with a 1-unit increase in variability (CRT ISD, BRT ISD); u_0i = between-person variance in the intercept of cognitive ability; u_1i = between-person variance in the slope of cognitive ability; e_jj = within-person variance.

p<0.05;

^**

p<0.01;

^***

p<0.001