. Author manuscript; available in PMC: 2017 Nov 1.

Published in final edited form as: Autism Res. 2016 Jun 8;9(11):1169–1182. doi: 10.1002/aur.1643

Table 7.

Parameter Estimates From the Nonlinear Mixed Effects (Exponential) Model Fitted to Head Circumference Data for the Typically Developing (TD), ASD With Normal-Sized Brains (ASD-N), and ASD With Disproportionate Megalencephaly (ASD-DM) Subgroups. Retrospective Head Circumference (HC) Measurements Were Obtained From Pediatric Medical Records (Well-Baby Visits) for Every Subject. The exponential Model Was Based on a Total of 1162 Measurements (Mean = 6.5 Per Subject, Standard Deviation = 4.12, Range = 18) That Spanned Birth Through 36 Months of Age

Model	Parameter (SE)	Group
Model	Parameter (SE)	TD	ASD-N	ASD-DM
Exponential	Asymptote (cm)	49.67 (0.19)	50.03 (0.14)^*	51.69 (0.25)^^,^*
	Intercept (cm)	34.93 (0.23)	34.92 (0.21)	36.16 (0.31)
	Rate	0.146 (0.004)	0.164 (0.004)^*	0.144 (0.006)
	Asymptote variance	1.23 (0.31)	1.34 (0.25)	0.46 (0.27)
	Intercept variance	1.60 (0.49)	2.64 (0.57)	0.73 (0.58)
	Rate variance	0.0001 (0.0001)	0.0004 (0.0002)	0.00002 (0.0001)
	Residual variance	0.49 (0.04)	0.64 (0.04)	0.95 (0.13)

Note. Significant contrast between TD and ASD-N

P < 0.05; significant contrast between TD and ASD-DM

^**

P < 0.0001; significant contrast between ASD-N and ASD-DM

^***

P < 0.0001.