Study participants' general characteristics according to sexual experience (weighted %).
| Characteristics | Middle school (n=119459) | High school (n=115108) | ||||
| Sexual experience | P value | Sexual experience | P value | |||
| No | Yes | No | Yes | |||
| % (SE) | % (SE) | % (SE) | % (SE) | |||
| Biological factors | ||||||
| Age, mean (SE) | 13.6 (0.00) | 13.9 (0.02) | <0.001 | 16.5 (0.00) | 16.8 (0.01) | <0.001 |
| Sex | <0.001 | <0.001 | ||||
| Boy | 96.6 (0.09) | 3.4 (0.09) | 89.6 (0.17) | 10.4 (0.17) | ||
| Girl | 98.4 (0.06) | 1.6 (0.06) | 94.9 (0.13) | 5.1 (0.13) | ||
| Psychological factors | ||||||
| Perceived stress | <0.001 | <0.001 | ||||
| Very low | 95.8 (0.29) | 4.2 (0.29) | 88.4 (0.57) | 11.6 (0.57) | ||
| Low | 98.0 (0.10) | 2.0 (0.10) | 92.8 (0.22) | 7.2 (0.22) | ||
| Middle | 97.9 (0.08) | 2.1 (0.08) | 93.2 (0.14) | 6.8 (0.14) | ||
| High | 97.6 (0.09) | 2.4 (0.09) | 92.5 (0.17) | 7.5 (0.17) | ||
| Very high | 94.8 (0.23) | 5.2 (0.23) | 87.8 (0.34) | 12.2 (0.34) | ||
| Suicidal thoughts | <0.001 | <0.001 | ||||
| No | 97.9 (0.06) | 2.1 (0.06) | 93.0 (0.12) | 7.0 (0.12) | ||
| Yes | 94.4 (0.21) | 5.6 (0.21) | 85.9 (0.35) | 14.1 (0.35) | ||
| Social factors | ||||||
| Family structure* | <0.001 | <0.001 | ||||
| Both parents | 98.0 (0.06) | 2.0 (0.06) | 93.5 (0.13) | 6.5 (0.13) | ||
| Single parent | 97.1 (0.16) | 2.9 (0.16) | 89.6 (0.28) | 10.4 (0.28) | ||
| Step-parent | 94.6 (0.69) | 5.4 (0.69) | 82.5 (1.07) | 17.5 (1.07) | ||
| None | 86.4 (0.93) | 13.6 (0.93) | 78.5 (0.90) | 21.5 (0.90) | ||
| Sex education | <0.001 | 0.049 | ||||
| No | 96.3 (0.15) | 3.7 (0.15) | 91.8 (0.20) | 8.2 (0.20) | ||
| Yes | 97.7 (0.06) | 2.3 (0.06) | 92.3 (0.14) | 7.7 (0.14) | ||
| Academic grade | <0.001 | <0.001 | ||||
| Low | 96.9 (0.11) | 3.1 (0.11) | 90.5 (0.18) | 9.5 (0.18) | ||
| Middle | 98.1 (0.08) | 1.9 (0.08) | 93.8 (0.15) | 6.2 (0.15) | ||
| High | 97.5 (0.09) | 2.5 (0.09) | 92.5 (0.18) | 7.5 (0.18) | ||
| Location of school | 0.731 | 0.096 | ||||
| Rural area | 97.7 (0.25) | 2.3 (0.25) | 91.4 (0.54) | 8.6 (0.54) | ||
| Medium and small city | 97.5 (0.09) | 2.5 (0.09) | 92.4 (0.18) | 7.6 (0.18) | ||
| Big city | 97.4 (0.09) | 2.6 (0.09) | 91.9 (0.20) | 8.1 (0.20) | ||
| Perceived economic level of household | <0.001 | <0.001 | ||||
| Low | 96.0 (0.19) | 4.0 (0.19) | 89.2 (0.26) | 10.8 (0.26) | ||
| Middle | 98.1 (0.06) | 1.9 (0.06) | 93.9 (0.13) | 6.1 (0.13) | ||
| High | 97.1 (0.09) | 2.9 (0.09) | 91.1 (0.19) | 8.9 (0.19) | ||
| Drinking | <0.001 | <0.001 | ||||
| No | 98.6 (0.05) | 1.4 (0.05) | 97.4 (0.08) | 2.6 (0.08) | ||
| Yes | 94.2 (0.16) | 5.8 (0.16) | 87.1 (0.20) | 12.9 (0.20) | ||
| Smoking | <0.001 | <0.001 | ||||
| No | 98.3 (0.05) | 1.7 (0.05) | 96.0 (0.08) | 4.0 (0.08) | ||
| Yes | 86.3 (0.45) | 13.7 (0.45) | 74.7 (0.36) | 25.3 (0.36) | ||
*The column included missing data (n=31406), including those who disagreed to respond to the survey on family members and those who responded by living with both their biological father and stepfather.
SE, standard error.