Table 1 Characteristics of study populations with and without ADHD symptoms
|  | Total % (n) | ADHD | χ 2 | |
|---|---|---|---|---|
Non-Symptomatic % (n) | Symptomatic % (n) | |||
Gender | ||||
 Male | 53.8 (501) | 85.5 (428) | 14.5 (73) | 14.456*** |
 Female | 46.2 (430) | 93.9 (404) | 6.1 (26) | |
Grade | ||||
 Three | 36.6 (342) | 87.3 (299) | 12.7 (43) | 2.187 |
 Four | 30.0 (280) | 90.6 (253) | 9.4 (27) | |
 Five | 33.4 (312) | 90.8 (283) | 9.2 (29) | |
Father’s education level | ||||
 Primary school and below | 3.7 (28) | 89.3 (25) | 10.7 (3) | 3.172 |
 Junior high school | 37.4 (286) | 88.1 (252) | 11.9 (34) | |
 Senior high school | 26.8 (205) | 89.8 (184) | 10.2 (21) | |
 College | 29.5 (226) | 92.5 (209) | 7.5 (17) | |
 Graduate | 2.6 (20) | 85.0 (17) | 15.0 (3) | |
Mother’s education level | ||||
 Primary school and below | 11.9 (91) | 87.9 (80) | 12.1 (11) | 1.634 |
 Junior high school | 35.8 (273) | 88.6 (242) | 11.4 (31) | |
 Senior high school | 24.0 (183) | 90.2 (165) | 9.8 (18) | |
 College | 27.7 (211) | 91.0 (192) | 9.0 (19) | |
 Graduate | 0.7 (5) | 100 (5) | 0 | |
Annual household income (USD) | ||||
  ≤ 3000 | 6.9 (50) | 88.0 (44) | 12.0 (6) | 1.080 |
 3000–6000 | 11.8 (86) | 88.4 (76) | 11.6 (10) | |
 6000–9000 | 19.5 (142) | 88.7 (126) | 11.3 (16) | |
 9000–12,000 | 14.4 (105) | 91.4 (96) | 8.6 (9) | |
 12,000–15,000 | 17.5 (127) | 89.8 (114) | 10.2 (13) | |
  ≥ 15,000 | 29.8 (217) | 90.8 (197) | 9.2 (20) | |
 Total | 100.0 (934) | 91.2 (852) | 8.8 (82) |  |