Table 1. Demographic characteristics of subjects (N =2430).
| Male (N = 1241) | Female (N = 1189) | p-value | |
|---|---|---|---|
| Age | 13.28 (±0.45) | 13.30 (±0.46) | 0.177 |
| Pubertal developmental scale at W1 | 9.47 (±2.25) | 11.35 (±2.11) | <0.001 |
| Body mass index at W1 | 20.43 (±4.19) | 19.51 (±3.18) | <0.001 |
| Body mass index at W3 | 21.04 (±3.98) | 20.32 (±3.15) | <0.001 |
| Family monthly income (NTD) | 0.827 | ||
| < 30000 | 203 (18.0) | 192 (16.1) | |
| 30000–60000 | 487 (43.2) | 481 (40.5) | |
| >60000 | 438 (38.8) | 409 (34.4) | |
| Internet use at W3 | <0.001 | ||
| < 1 hour/week | 272 (21.9) | 439 (36.9) | |
| 1–2 hours/week | 215 (17.3) | 332 (27.9) | |
| 3–5 hours/week | 262 (21.1) | 244 (20.5) | |
| 6–10 hours/week | 159 (12.8) | 107 (9.0) | |
| 11–20 hours/week | 147 (11.8) | 43 (3.6) | |
| > 20 hours/week | 186 (15.0) | 24 (2.0) | |
| Leisure purpose of Internet use at W3 | |||
| Chatting | 340 (27.4) | 519 (43.7) | <0.001 |
| Gaming | 870 (70.1) | 256 (21.5) | <0.001 |
| Non-academic browsing | 499 (40.2) | 661 (55.6) | <0.001 |
| Pornography viewing | 77 (6.2) | 4 (0.3) | <0.001 |
Data are presented as n (%) or mean (± standard deviation). Comparison of variables between male and female participants was examined by student t test and χ2 test accordingly. NTD represents New Taiwan Dollar; W1, Wave 1; W3, Wave 3.