Table 2.

Summary of hierarchical regression analyses predicting blood Phe levels at 8–10 years of age.

Model	R2	Adj R2	F	df	Significant contributors
					Variable	t	Beta
1	0.03	0.01	1.28	(1,35)
2	0.19	0.14	4.22⁎	(2,34)	Phe-2	2.65⁎	0.49
3	0.32	0.26	5.59⁎⁎	(3,33)	Phe-3	2.63⁎	0.49
4	0.33	0.26	4.38⁎⁎	(4,32)	Phe-3	2.04⁎	0.42
5	0.40	0.31	4.52⁎⁎	(5,31)
6	0.42	0.32	4.0⁎⁎	(6,30)
7	0.60	0.51	6.90⁎⁎	(7,29)	Phe-7	3.80⁎⁎	0.75

Note. Phe-2 = Phe at 12–23 months of age, Phe-3 = Phe at 24–35 months of age, Phe-5 = Phe at 4 years to 4 years 11 months of age, Phe-7 = Phe at 6 years to 7 years 11 months of age.

Predictors. Model 1: (constant), Phe at 1–11 months of age.

Model 2: (constant), Phe at 1–11 months of age, Phe at 12–23 months of age.

Model 3: (constant), Phe at 1–11 months of age, Phe at 12–23 months of age, Phe at 24–35 months of age.

Model 4: (constant), Phe at 1–11 months of age, Phe at 12–23 months of age, Phe at 24–35 months of age, Phe at 3 years to 3 years 11 months.

Model 5: (constant), Phe at 1–11 months of age, Phe at 12–23 months of age, Phe at 24–35 months of age, Phe at 3 years to 3 years 11 months, Phe at 4 years to 4 years 11 months.

Model 6: (constant), Phe at 1–11 months of age, Phe at 12–23 months of age, Phe at 24–35 months of age, Phe at 3 years to 3 years 11 months, Phe at 4 years to 4 years 11 months, Phe at 5–6 years of age.

Model 7: (constant), Phe at 1–11 months of age, Phe at 12–23 months of age, Phe at 24–35 months of age, Phe at 3 years to 3 years 11 months, Phe at 4 years to 4 years 11 months, Phe at 5–6 years of age, Phe at 6–8 years of age.

^⁎p < 0.05.

^⁎⁎p < 0.01.