Table 2.

Model results for the three-class linear model for twins and singletons

	Twins			Singletons
	Est	SE	p value	Est	SE	p value
Boys
Class#1: stable low
I	2.06	0.10	<0.001	1.97	0.20	<0.001
S	−0.03	0.02	0.16	0.03	0.03	0.34
Class#2: low-increasing
I	4.04	0.19	<0.001	3.39	0.74	0.001
S	0.83	0.14	<0.001	0.92	0.14	<0.001
Class#3: high-decreasing
I	8.85	0.52	<0.001	8.56	0.93	<0.001
S	−0.80	0.10	<0.001	−0.56	0.13	0.002
Girls
Class#1: stable low
I	1.13	0.08	<0.001	1.09	0.13	<0.001
S	−0.02	0.02	0.23	0.02	0.03	0.49
Class#2: low-increasing
I	2.66	0.19	<0.001	2.09	0.49	<0.001
S	0.59	0.14	<0.001	0.71	0.20	<0.001
Class#3: high-decreasing
I	6.43	0.34	<0.001	6.97	1.19	<0.001
S	−0.60	0.07	<0.001	−0.48	0.11	<0.001

BIC boys 63,945.99, BIC girls 60,683.19, I intercept, S linear slope, Est estimated mean, SE standard error, p value significance of intercept and slope means, Intercept variances are freely estimated, slope variances are fixed to zero