Table 1 General information of 5451 schoolchildren aged 11–17
| Â | N | % |
|---|---|---|
Gender | ||
 Male | 2678 | 49.13 |
 Female | 2773 | 50.87 |
Age | ||
 11–14 | 2872 | 52.69 |
 15–17 | 2579 | 47.31 |
 Single child (yes/no) | 3604 | 66.12 |
Mather education | ||
 Primary | 1201 | 22.03 |
 Junior | 2343 | 42.98 |
 Senior | 1294 | 23.74 |
 College | 613 | 11.25 |
 Parental divorced (yes/no) | 399 | 7.32 |
SDQ informants | ||
 Self | 5449 | 99.96 |
 Parent | 5095 | 93.47 |
 Teacher | 5342 | 98.00 |
Number of informants | ||
 1 | 2 | 0.04 |
 2 | 463 | 8.49 |
 3 | 4986 | 91.47 |
 All | 5451 | 100.00 |