Table 2. General characteristics of participants by the occurrence of ADHD.

	n	%	ADHD		Non-ADHD
			n	%	n	%
Total	18,029		554	3.1	17,475	96.9
Income
Quartile 1 (low)	1117	6.2	41	3.7	1076	96.3
Quartile 2 (mid-low)	5171	28.7	168	3.2	5003	96.8
Quartile 3 (mid-high)	8576	47.6	241	2.8	8335	97.2
Quartile 4 (high)	3165	17.6	104	3.3	3061	96.7
Income trajectory
Consistently low	1026	5.7	40	3.9	986	96.1
Consistently mid-low	3039	16.9	107	3.5	2932	96.5
Mid-low to mid-high	1632	9.1	47	2.9	1585	97.1
Consistently mid-high	7525	41.7	203	2.7	7322	97.3
Decreasing	911	5.1	39	4.3	872	95.7
Mid-high to high	642	3.6	16	2.5	626	97.5
Consistently high	3254	18.0	102	3.1	3152	96.9
Sex
Men	9388	52.1	430	4.6	8958	95.4
Women	8641	47.9	124	1.4	8517	98.6
Location
Rural	5490	30.5	128	2.3	5362	97.7
Urban	12,539	69.5	426	3.4	12,113	96.6
Low birth weight (<2500 g)
No	17,894	99.3	548	3.1	17,346	96.9
Yes	135	0.7	6	4.4	129	95.6
Conduct disorders (aggressive disorder, oppositional defiant disorder)
No	18,009	99.9	546	3.0	17,463	97.0
Yes	20	0.1	8	40.0	12	60.0
Emotional disorders (depression, anxiety)
No	17,808	98.8	512	2.9	17,296	97.1
Yes	221	1.2	42	19.0	179	81.0
Social disorders
No	18,003	99.9	542	3.0	17,461	97.0
Yes	26	0.1	12	46.2	14	53.8
Tic disorders
No	17,830	98.9	523	2.9	17,307	97.1
Yes	199	1.1	31	15.6	168	84.4
Autism spectrum disorders
No	18,000	99.8	541	3.0	17,459	97.0
Yes	29	0.2	13	44.8	16	55.2
Developmental disorders
No	17,763	98.5	500	2.8	17,263	97.2
Yes	266	1.5	54	20.3	212	79.7
Intellectual disability
No	17,950	99.6	537	3.0	17,413	97.0
Yes	79	0.4	17	21.5	62	78.5
Year of birth
2002	9109	50.5	309	3.4	8800	96.6
2003	8920	49.5	245	2.7	8675	97.3

ADHD, attention deficit hyperactivity disorder.