Distribution of variables in total sample and according to smoking status at age 50 (N=8218)
| Variable | Total sample (N=8218) | Smokers (n=1677, 20.4%) | Non-smokers (n=6541, 79.6%) | Difference between smokers and non-smokers |
|---|---|---|---|---|
| Sex | ||||
| Male | 4221 (51.4%) | 851 (50.7%) | 3370 (51.5%) | |
| Female | 3997 (48.6%) | 826 (49.3%) | 3171 (48.5%) | p=0.58 |
| Social class at birth | ||||
| I | 402 (4.9%) | 52 (3.1%) | 350 (5.4%) | |
| II | 1182 (14.4%) | 175 (10.4%) | 1007 (15.4%) | |
| IIIN | 842 (10.3%) | 146 (8.7%) | 696 (10.6%) | |
| IIIM | 3900 (47.4%) | 810 (48.3%) | 3090 (47.2%) | |
| IV | 911 (11.1%) | 202 (12.1%) | 709 (10.8%) | |
| V | 981 (11.9%) | 292 (17.4%) | 689 (10.6%) | p<0.001 |
| Cognitive ability at 7 (1/5ths ‘draw-a-man’) | ||||
| Lowest | 1641 (20.0%) | 383 (22.8%) | 1258 (19.2%) | |
| 2nd | 1675 (20.4%) | 376 (22.4%) | 1299 (19.9%) | |
| Middle | 1732 (21.1%) | 338 (20.2%) | 1394 (21.3%) | |
| 4th | 1501 (18.2%) | 292 (17.4%) | 1209 (18.5%) | |
| Highest | 1669 (20.3%) | 288 (17.2%) | 1381 (21.1%) | p<0.001 |
| Childhood conduct at 7 | ||||
| Mean (SD) | −0.28 (2.14) | 0.10 (2.38) | −0.38 (2.06) | p<0.001 |
| Minimum/maximum | −7.68/17.57 | −5.60/17.57 | −7.68/13.87 | |
| Attention problems at 7 | ||||
| Never | 5723 (69.6%) | 1115 (66.5%) | 4608 (70.5%) | |
| Sometimes | 1979 (24.1%) | 433 (25.8%) | 1545 (23.6%) | |
| Frequently | 516 (6.3%) | 129 (7.7%) | 388 (5.9%) | p<0.001 |
| Childhood conscientiousness | ||||
| Mean (SD) | 10.58 (2.81) | 9.39 (2.79) | 10.88 (2.73) | p<0.001 |
| Minimum/maximum | 3.00/15.00 | 3.00/15.00 | 3.00/15.00 | |
| Social class at 50 | ||||
| I | 510 (6.2%) | 50 (3.0%) | 460 (7.0%) | |
| II | 3382 (41.2%) | 541 (32.3%) | 2841 (43.4%) | |
| IIIN | 1634 (19.9%) | 313 (18.7%) | 1321 (20.2%) | |
| IIIM | 1554 (18.9%) | 420 (25.0%) | 1134 (17.3%) | |
| IV | 907 (11.0%) | 273 (16.3%) | 634 (9.7%) | |
| V | 231 (2.8%) | 80 (4.8%) | 151 (2.3%) | p<0.001 |
| Qualifications at 50 (NVQ level) | ||||
| None | 691 (8.4%) | 256 (15.3%) | 435 (6.7%) | |
| 1 | 934 (11.4%) | 267 (15.9%) | 667 (10.2%) | |
| 2 | 2144 (26.1%) | 468 (27.9%) | 1676 (25.6%) | |
| 3 | 1451 (17.7%) | 275 (16.4%) | 1176 (18.0%) | |
| 4 | 2657 (32.3%) | 374 (22.3%) | 2283 (34.9%) | |
| 5–6 | 341 (4.1%) | 37 (2.2%) | 304 (4.6%) | p<0.001 |
| Conscientiousness at 50 | ||||
| Mean (SD) | 33.87 (5.34) | 33.33 (5.47) | 34.00 (5.29) | p<0.001 |
| Minimum/maximum | 11.00/50.00 | 15.00/48.00 | 11.00/50.00 | |
NVQ, National Vocational Qualifications.