Table 2.

Hypothesis testing. The final models used in the SAS PROC MIXED regression analyses after backward step-wise elimination. The models at each step were hierarchically well formulated. All terms not retained in the analyses were excluded at a p > .10

		All subjects n = 40			ADHD excluded n = 35			OCD excluded n = 36			Medication-free only n = 31
Source	NDF	DDF	F	p	DDF	F	p	DDF	F	p	DDF	F	p
Region	4	155	9.74	<.001	135	8.04	.001	140	8.77	<.001	119	7.20	<.001
TS	1	38	7.60	.009	33	6.64	.015	35	6.41	.016	29	9.39	.005
Age	1	38	2.17	.150	33	.98	.330	35	2.97	.094	29	1.73	.199

NDF = numerator degrees of freedom; DDF = denominator degrees of freedom; F = F statistic for Type III sum of squares; p = probability values; TS = group (TS or HC).