Table 2.

Comparisons of Early Behavioral and Cognitive Predictors Across High- and Low-ADHD Groups

		Males				Females
Month	Measure	Low- ADHD	High- ADHD	t	d	Low- ADHD	High- ADHD	t	d
1	Early Infant Temperament	3.346	3.408	.876	0.099	3.271	3.330	.624	0.091
6	Early Infant Temperament	3.117	3.204	1.78	0.221	3.172	3.194	.490	0.055
	Activity Level – Semi Structured Play	2.466	2.527	.912	0.105	2.441	2.442	.022	0.003
15	Bayley MDI	109.73	107.70	−1.282	0.150	112.24	105.35	−3.646***	0.528
	Highest Level of Play	4.182	4.200	.361	0.025	4.412	4.400	−.451	0.019
24	Bayley MDI	94.55	91.92	−2.109*	0.239	98.00	93.51	−2.776**	0.400
	Highest Level of Play	4.610	4.766	2.830**	0.269	4.756	4.736	−.811	0.043
	Activity Level – Semi Structured Play	2.713	2.768	.839	0.096	2.709	2.731	.241	0.035
	CBCL Externalizing	13.740	17.394	4.234***	0.509	13.214	17.434	4.122***	0.620
	CBCL Internalizing	7.590	8.958	2.281*	0.290	7.662	9.057	2.118*	0.296
	CBCL Sleep Problems	3.132	3.970	2.732**	0.311	2.945	4.137	3.193**	0.459
	CBCL Somatic Problems	2.795	2.772	−.091	0.010	2.682	3.224	1.789	0.259
	CBCL Total Problems	34.442	42.074	3.994***	0.451	33.636	42.830	3.906***	0.559
36	Reynell Vocabulary Comprehension	99.858	93.775	−3.336**	0.408	104.027	100.711	−1.546	0.243
	Reynell Expressive Language	97.942	97.282	−.382	0.048	101.407	99.535	−.911	0.146
	Highest Level of Play	4.523	4.674	2.252*	0.247	4.727	4.560	−1.784	0.334
	CBCL Externalizing	12.288	17.401	6.211***	0.702	12.376	16.258	3.997***	0.587
	CBCL Internalizing	7.704	9.786	3.749***	0.434	8.299	10.080	2.459*	0.365
	CBCL Sleep Problems	3.497	4.481	3.009**	0.378	3.441	4.768	3.054**	0.517
	CBCL Somatic Problems	2.711	3.398	2.534*	0.296	2.829	3.344	1.484	0.221
	CBCL Total Problems	33.399	44.589	5.654***	0.643	34.316	43.443	3.743***	0.551
	Bracken School Readiness	15.268	10.641	−4.302***	0.490	17.830	15.400	−1.629	0.243

Note: t=t-value for two-tailed, independent samples t-test.

^*p<.05

^**p<.01

^***p<.001

d=Cohen’s d effect size value. Bold print indicates a modest or large effect size (d>.3).