Table 1. Characteristics of the Study Sample.

Characteristics	Male	Female	Total
Sample size, n (%)	638(57.9)	463 (42.1)	1101 (100.0)
Age in years
13 and younger, n (%)	313 (55.4)	252 (44.6)	565 (100)
14 and older, n (%)	325(60.6)	211(39.4)	536(100)
Mean (SD)	13.8(1.2)	13.7(1.2)	13.8(1.2)
School grade, n (%)
Grade 7	326(57.6)	240(42.4)	566(100)
Grade 8	129(58.4)	94(41.6)	221(100)
Grade 9	183(58.3)	131(41.7)	314(100)
YIAT-C score**
Mean score (SD)	37.4(12.6)	33.9(10.7)	36.0(11.9)
Parental relationship
Mean score (SD)	46.6(10.8)	46.3 (11.9)	46.5(11.3)
Hyperactivity-Impulsivity
Mean score (SD)	3.6(2.1)	3.9(2.2)	3.7(2.1)

Note: **: p<0.01 from t-test.