|  | Weekly physical activitiesc | |||||
---|---|---|---|---|---|---|---|
Item | Â | Â | High | Low | Â | ||
 |  |  | Mean | SE | mean | SE | P-valuea |
Age | Â | Â | 8.95 | 0.027 | 9.2 | 0.031 | Â |
Height |  |  | 134.0 | 0.18 | 135.2 | 0.21 | < 0.001 |
Weight |  |  | 29.9 | 0.13 | 31.2 | 0.16 | < 0.001 |
 |  | N | N | % | n | % | P-valueb |
Gender | Boys | 3619 | 2161 | 59.7 | 1458 | 40.3 | < 0.001 |
Girls | 3429 | 1605 | 46.8 | 1824 | 53.2 | Â | |
School year | 1 | 1393 | 756 | 54.3 | 637 | 45.7 | < 0.001 |
2 | 1283 | 723 | 56.4 | 560 | 43.6 | Â | |
3 | 1218 | 705 | 57.9 | 513 | 42.1 | Â | |
4 | 1180 | 670 | 56.8 | 510 | 43.2 | Â | |
5 | 1111 | 560 | 50.4 | 551 | 49.6 | Â | |
6 | 863 | 352 | 40.8 | 511 | 59.2 | Â |