Table 4.

Results of Hierarchical Linear Models of Impulsivity

Fixed Effects	B	SE	t	p-value	Variance-Covariance Components Test
					Deviance	χ2 statistic	p-value
	Effects of Time
Intercept	6.746	0.473	14.270	<0.001
Age	0.006	0.542	0.012	0.991	4918.315	1602.266	<0.001
Linear Effect of Time	1.520	0.409	3.718	<0.001
Age	0.291	0.465	0.626	0.532	4894.309	23.691	<0.001
Quadratic Effect of Time	-0.323	0.080	-4.060	<0.001
Age	-0.801	0.091	-0.891	0.374	4878.495	15.814	0.002
	Effects of Gender
Intercept	6.750	0.473	14.281	<0.001
Age	-0.027	0.540	-0.049	0.961
Gender	0.923	0.942	0.980	0.328	4919.039	1599.520	<0.001
Linear Effect of Time	1.517	0.409	3.710	<0.001
Age	0.305	0.461	0.662	0.509
Gender	-0.474	0.817	-0.580	0.562	4894.508	24.531	<0.001
Quadratic Effect of Time	-0.323	0.080	-4.051	<0.001
Age	-0.083	0.090	-0.922	0.357
Gender	0.055	0.162	0.342	0.733	4882.176	12.332	0.007
	Effects of Race
Intercept	6.762	0.473	14.295	<0.001
Age	-0.027	0.540	-0.049	0.961
Contrast 1	-0.796	1.261	-0.631	0.529
Contrast 2	-2.144	1.417	-1.513	0.131	4915.883	1596.527	<0.001
Linear Effect of Time	1.483	0.398	3.723	<0.001
Age	0.305	0.462	0.662	0.509
Contrast 1	0.654	1.069	0.612	0.541
Contrast 2	1.629	1.174	1.387	0.167	4893.702	22.181	<0.001
Quadratic Effect of Time	-0.317	0.077	-4.107	<0.001
Age	-0.083	0.09	-0.992	0.357
Contrast 1	-0.098	0.205	-0.475	0.635
Contrast 2	-0.308	0.223	-1.381	0.169	4878.387	15.315	0.002

Note. Race Contrast 1 compared differences between White and Black adolescents. Race Contrast 2 compared Black adolescents to adolescents who belonged to the “Other” racial group.