Baseline characteristics of students according to study condition
| Control n (%valid) | Intervention n (%valid) | |
| Total (n=11 316) | 5567 (49.2) | 5749 (50.8) |
| Gender | ||
| Male | 2787 (51.1) | 2834 (50.0) |
| Female | 2670 (48.9) | 2829 (50.0) |
| Missing | 110 | 86 |
| Free school meals | ||
| No | 4289 (77.3) | 4436 (77.5) |
| Yes | 1258 (22.7) | 1290 (22.5) |
| Missing | 20 | 23 |
| Location | ||
| NI | 3469 (62.3) | 3554 (61.8) |
| Scotland | 2098 (37.7) | 2198 (38.2) |
| Missing | 0 | 0 |
| Heavy episodic drinking* | ||
| No | 5082 (92.2) | 5261 (92.4) |
| Yes | 432 (7.8) | 431 (7.6) |
| Missing | 53 | 57 |
| Ethnicity | ||
| White | 4492 (95.3) | 4495 (94.5) |
| Non-white | 248 (4.5) | 293 (5.5) |
| Missing | 827 | 961 |
The percentages are calculated on the basis of the complete cases only.
*Assessed at baseline as consuming >5 drinks in one or more episodes in the last 30 days.