Description of sample before and after smoke-free legislation in Scotland
| Characteristic | 2006 (n = 2527) | 2007 (n = 2379) |
| Mean age (years) | 11.5 (SD 0.36) | 11.4 (SD 0.36) |
| Boys | 1285 (50.9) | 1221 (51.3) |
| Family affluence scale*: | (n = 2443) | (n = 2251) |
| Low | 908 (37.2) | 765 (34.0) |
| Medium | 732 (30.0) | 701 (31.1) |
| High | 803 (32.9) | 785 (34.9) |
| Cotinine confirmed smoking status†: | (n = 2527) | (n = 2379) |
| Non-smokers | 2335 (92.4) | 2210 (92.9) |
| Smokers | 45 (1.8) | 35 (1.5) |
| Missing‡ | 147 (5.8) | 134 (5.6) |
| Family structure (parent figures that sample lives with): | (n = 2527) | (n = 2379) |
| Both parents | 1722 (68.1) | 1596 (67.1) |
| Parent and step-parent | 240 (9.5) | 229 (9.6) |
| Single mother | 451 (17.8) | 431 (18.1) |
| Single father | 45 (1.8) | 40 (1.7) |
| Other§ | 36 (1.4) | 35 (1.5) |
| Unclassifiable | 16 (0.6) | 33 (1.4) |
| Missing | 17 (0.7) | 15 (0.6) |
Values are numbers (%) unless stated otherwise.
*Pupils who reported living in both parent, step or single parent families only.
†Non-smokers, self reported non-smokers with cotinine concentrations ⩽15 ng/ml; smokers, cotinine concentrations >15 ng/ml regardless of self-reported smoking status.
‡Pupils who did not answer the smoking question or have a cotinine concentration assigned to them by the laboratory.
§Pupils who reported to be living in a foster home or children’s home or some other arrangement.