Table 1.

participants' background variables.

Age category		ADHD (N = 559)		Control (N = 365)		Difference
6	N	107		53
	Male	76 (71.03%)		27 (50.94%)		χ2(1,N = 160) = 6.23*
	female	31 (28.97%)		26 (49.06%)
	Age M (SD)	6.53	(0.30)	6.57	(0.27)	t(158)= −0.88
7	N	111		94
	Male	73 (65.77%)		39 (41.49%)		χ2(1,N = 205) = 12.20***
	female	38 (34.23%)		55 (58.51%)
	Age M (SD)	7.45	0.02	7.46	0.03	t(203) = −0.22
8		112		70
	Male	66 (58.93%)		33 (47.14%)		χ2(1,N = 182) = 2.41
	female	46 (41.07%)		37 (52.86%)
	Age M (SD)	8.51	0.28	8.45	0.32	t(180) = 1.30
9	N	93		57
	Male	56 (60.22%)		33 (57.89%)		χ2(1,N = 150) = 0.08
	female	37 (39.78%)		24 (42.11%)
	Age M (SD)	9.51	0.27	9.53	0.28	t(148) = −0.31
10	N	77		59
	Male	47 (61.04%)		32 (54.24%)		χ2(1,N = 136) = −0.63
	female	30 (38.96%)		27 (45.76%)
	Age M (SD)	10.46	0.31	10.60	0.28	t(134) = −2.67**
11	N	59		32
	Male	39 (66.10%)		18 (56.25%)		χ2(1,N = 91) = 0.86
	female	20 (33.90%)		14 (43.75%)
	Age M (SD)	11.50	0.33	11.39	0.28	t(89)= 1.47

^*p < 0.05;

^**p < 0.01;

^***p < 0.001.