| n | Mean (SD) | % of sample |  | n | Mean (SD) | % of sample |
---|---|---|---|---|---|---|---|
Mandatory sample (Twente) | Â | Â | Â | Voluntary sample (IJsselland) | Â | Â | Â |
Age | 8761 | 14.23 (1.14) | - | Age | 1571 | 14.29 (1.07) | - |
Educationa | 9295 | - | 51.5 | Educationa | 1723 | - | 61.3 |
Genderb | 9359 | - | 49.2 | Genderb | 1952 | - | 55.8 |
School experiencesc | 9354 | 2.52 (.85) | - | School experiencesc | 1913 | 2.13 (.73) | - |
Subjective healthd | 9356 | 1.85 (.70) | - | Subjective healthd | 1892 | 1.75 (.69) | - |
SDQ | 9349 | - | - | SDQ | 1952 | - | - |
 Unlikely | 8275 | - | 88.5 | Unlikely | 1712 | - | 91.3 |
 Possible | 753 | - | 8.1 | Possible | 104 | - | 5.5 |
 Probable | 321 | - | 3.4 | Probable | 60 | - | 3.2 |
Tobacco consumptione | 9291 | - | 9.13 | Tobacco consumptione | 1951 | - | 3.5 |
Alcohol consumptionf | 9015 | - | 51.8 | Alcohol consumptionf | 1944 | - | 26.2 |
Lifetime alcohol consumptiong | 9280 | 5.67 (5.26) | - | Lifetime alcohol consumptiong | 1684 | 2.31 (3.48) | - |
Alcohol in past four weeksh | 9272 | - | 41.5 | Alcohol in past four weeksh | 1678 | - | 11.1 |
Sexual intercoursei | 9247 | 1.28 (.79) | - | Sexual intercoursei | 1649 | 1.13 (.55) | - |