Table 3. Estimates from best fit polynomial growth curve models for longitudinal measurements of BMI z-scores.

	White			Black
Variable	Coef	SE	p-value	Coef	SE	p-value
Intercept	0.424	0.088	<.0001	0.460	0.121	0.0002
Early maturity	0.0042	0.0999	0.97	0.117	0.104	0.26
Low family SES	0.330	0.103	0.001	0.162	0.100	0.105
Neighborhood median family income ($1000 increase)	--	--	--	0.0048	0.0014	0.0008
Age	-0.0014	0.0064	0.83	-0.037	0.022	0.09
Age × low family SES	-0.0055	0.0116	0.63	0.029	0.014	0.03
Age × neighborhood median family income				0.000005	0.00051	0.99
Age2	-0.0073	0.0015	<0.0001	-0.0045	0.0037	0.22
Age2 × low family SES	-0.0032	0.0027	0.24	-0.0072	0.0022	0.001
Age2 × neighborhood median family income	--	--	--	0.000033	0.000092	0.72
Age3	--	--	--	0.0025	0.0010	0.01
Age3 × low family SES	--	--	--	-0.0010	0.0006	0.08
Age3 × neighborhood median family income	--	--	--	-0.00001	0.000024	0.56
Random effect variance parameter estimates	Estimate	SE	p-value	Estimate	SE	p-value
Intercept	0.68	0.06	<0.0001	0.84	0.07	<0.0001
Age	0.0050	0.0008	<0.0001	0.004	0.0007	<0.0001
Age2	0.00011	0.00004	0.006	0.00004	0.00003	0.11
AR-1	0.47	0.06	<0.0001	0.56	0.07	<0.0001
Residual	0.13	0.02	<0.0001	0.12	0.02	<0.0001

AR-1, first order autoregressive process correlation parameter; SE, standard error; SES, socioeconomic status;