Demographic characteristics of overall and different schools
| Variables | Overall (n=89 360) | Primary (n=26 235, 29.4) | Junior high (n=42 683, 47.7) | Senior high (n=20 442, 22.9) |
| Age* | 13.4±2.1 | 11.0±0.74 | 13.4±0.99 | 16.2±1.13 |
| Gender | ||||
| Boys | 44 653 (50.0) | 13 492 (51.4) | 21 941 (51.4) | 9220 (45.1)† |
| Girls | 44 707 (50.0) | 12 743 (48.6) | 20 742 (48.6) | 11 222 (54.9) |
| Residence* | ||||
| Urban | 53 189 (59.5) | 15 740 (60.0) | 24 208 (56.7) | 13 241 (64.8) |
| Rural | 36 171 (40.5) | 10 495 (40.0) | 18 475 (43.3) | 7201 (35.2) |
| Nuclear family* | ||||
| Yes | 70 278 (78.6) | 19 907 (75.9) | 33 467 (78.4) | 16 904 (82.7) |
| No | 19 028 (21.4) | 6328 (24.1) | 9216 (21.6) | 3538 (17.3) |
| LBC | ||||
| Yes | 29 986 (33.6) | 7831 (29.8)† | 14 981 (35.1) | 7174 (35.1) |
| No | 59 374 (66.4) | 18 404 (70.2) | 27 702 (64.9) | 13 268 (64.9) |
| Paternal drinks* | ||||
| Yes | 66 804 (74.8) | 18 265 (69.6) | 32 453 (76.0) | 16 086 (78.7) |
| No | 22 556 (25.2) | 7970 (30.4) | 10 230 (24.0) | 4356 (21.3) |
| Maternal drinks* | ||||
| Yes | 21 420 (24.0) | 5045 (19.2) | 10 312 (24.2) | 6063 (29.7) |
| No | 67 940 (76.0) | 21 190 (80.8) | 32 371 (75.8) | 14 379 (70.3) |
| Drinker | ||||
| Yes | 17 007 (19.0) | 4935 (18.8) | 8230 (19.3) | 3842 (18.8) |
| No | 72 353 (81.0) | 21 300 (81.2) | 34 453 (80.7) | 16 600 (81.2) |
| Hazardous drinking | ||||
| Yes | 1848 (2.1) | 330 (1.3)† | 999 (2.3) | 519 (2.5) |
| No | 87 512 (97.9) | 25 905 (98.7) | 41 684 (97.7) | 19 923 (97.5) |
Data are number (percentage) or mean±SD. Nuclear family, which means that students live with their two biological parents.
*There are significant differences among the three schools.
†The variable of this group is significantly different from the others (p<0.05).
LBC, left-behind children.