. 2017 Aug 2;74(8):815–822. doi: 10.1001/jamapsychiatry.2017.1472

Table 1. Characteristics of Individuals With ADHD and Matched Population Control Individuals Who Had Taken the SweSAT.

Characteristic	Group^a		P Value for Test of Group Differences^c
Characteristic	Patients With ADHD (n = 3718)	Matched Controls (n = 8371)^b	P Value for Test of Group Differences^c
No. of tests per person	1.58 (1.09)	1.74 (1.20)	<.001
Age at test, y	22.10 (3.30)	20.55 (2.44)	<.001
Test score	91.40 (46.16)	90.51 (43.02)	.20
IQ in stanine scores^d	5.62 (1.82)	5.86 (1.74)	.002
Highest educational level >12 y of education, No. (%)
Father	1667 (44.84)	3851 (46.00)	.29
Mother	1921 (51.67)	4320 (51.61)	.60

Abbreviations: ADHD, attention-deficit/hyperactivity disorder; SweSAT, Swedish Scholastic Aptitude Test.

^{^a}

Data are presented as mean (SD) unless otherwise indicated.

^{^b}

Population controls were matched with each patient with ADHD on sex, birth year, and residential area at the time of diagnosis at a ratio of 10:1. A total of 8371 individuals from 37 180 matched controls had taken the test during the study follow-up.

^{^c}

Two-sided t tests were used for continuous variables. χ² Tests were used for 2 × 2 contingency table with Yates correction.

^{^d}

Based on 20% nonmissing IQ data in males.