Table 1.
Baseline characteristics of the participating youths
| Variables | Percentage or mean ± standard deviation | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| High school students | Undergraduate students | Graduate students | All (n = 10,082) | |||||||
| Male (n = 678) | Female (n = 2146) | Total (n = 2824) | Male (n = 2106) | Female (n = 4918) | Total (n = 7024) | Male (n = 68) | Female (n = 166) | Total (n = 234) | ||
| Age (years) | 17.5 ± 1.2 | 17.5 ± 1.2 | 17.5 ± 1.2 | 20.6 ± 2.0 | 20.6 ± 1.6 | 20.6 ± 1.8 | 24.3 ± 4.1 | 24.7 ± 3.2 | 24.6 ± 3.5 | 19.8 ± 2.3 |
| Ethnic | ||||||||||
| Han | 96.9 | 96.7 | 96.7 | 94.2 | 95.1 | 94.8 | 92.6 | 92.2 | 92.3 | 95.3 |
| Minority | 3.1 | 3.3 | 3.3 | 5.8 | 4.9 | 5.2 | 7.4 | 7.8 | 7.7 | 4.7 |
| Urbanicity | ||||||||||
| Urban | 31.9 | 22.1 | 24.4 | 40.2 | 41.3 | 41.0 | 57.4 | 63.3 | 61.5 | 36.8 |
| Non-urban | 68.1 | 77.9 | 75.6 | 59.8 | 58.7 | 59.0 | 42.6 | 36.7 | 38.5 | 63.2 |
| Region | ||||||||||
| Northeast | – | – | – | 0.3 | 0.2 | 0.3 | 2.9 | 4.2 | 3.8 | 0.3 |
| East | 0.6 | 0.7 | 0.7 | 10.1 | 12.2 | 11.5 | 25.0 | 28.3 | 27.4 | 8.9 |
| West | 99.4 | 99.3 | 99.3 | 85.5 | 84.1 | 84.5 | 61.8 | 50.0 | 53.4 | 87.9 |
| Central | – | – | – | 4.1 | 3.5 | 3.7 | 10.3 | 17.5 | 15.4 | 2.9 |
| Household income (CNY/year) | ||||||||||
| < 12,000 | 20.8 | 25.7 | 24.5 | 21.7 | 18.5 | 19.4 | 13.2 | 4.2 | 6.8 | 20.6 |
| 12,000–19,999 | 28.0 | 37.9 | 35.6 | 23.2 | 28.2 | 26.7 | 4.4 | 11.4 | 9.4 | 28.8 |
| 20,000–59,999 | 28.3 | 25.0 | 25.8 | 26.4 | 28.1 | 27.6 | 14.7 | 24.7 | 21.8 | 27.0 |
| 60,000–99,999 | 15.2 | 7.8 | 9.6 | 14.8 | 13.4 | 13.8 | 22.1 | 22.9 | 22.6 | 12.8 |
| 100,000–199,999 | 5.5 | 2.6 | 3.3 | 9.4 | 8.6 | 8.9 | 27.9 | 24.7 | 25.6 | 7.7 |
| ≥ 200,000 | 2.2 | 1.0 | 1.3 | 4.6 | 3.2 | 3.6 | 17.6 | 12.0 | 13.7 | 3.2 |
| Major | ||||||||||
| Medical science | 59.0 | 98.4 | 89.0 | 12.4 | 16.0 | 14.9 | 41.2 | 52.4 | 49.1 | 36.4 |
| Science/engineering | 39.4 | 1.0 | 10.2 | 51.9 | 22.6 | 31.4 | 44.1 | 20.5 | 27.4 | 25.4 |
| Social science | 1.6 | 0.6 | 0.8 | 35.7 | 61.4 | 53.7 | 14.7 | 27.1 | 23.5 | 38.2 |
All variables were significantly different (P < 0.05) across educational levels (high school students, undergraduate students, graduate students) within the overall population and within a given sex (male, female). Values under a given variable were shown in bold, if the difference between sexes within a given educational level was significant (P < 0.05)