Table 1. Comparisons between those with complete data and those with KS2 data but incomplete data on demographic and other variables.
| Complete dataset | Incomplete dataset (KS2 data only) | ||
| N | Mean [SD] | Mean [SD] | |
| KS2 score | 11,974 | 7,062 | 4,912 |
| 102.4 [8.9] | 98.4 [10.4] | ||
| N | % | % | |
| sex | 11,974 | 7,062 | 4,912 |
| male | 6097 | 50.6 | 51.4 |
| female | 5877 | 49.4 | 48.6 |
| χ 2 = 0.66 p = 0.42 | |||
| Marital Status | 11,273 | 7,062 | 4,912 |
| married | 8521 | 81.9 | 65.1 |
| never married | 2111 | 13.6 | 27.3 |
| wid/separated | 641 | 4.5 | 7.6 |
| χ 2 = 407.21 p = 0.0001 | |||
| Ethnicity | 10,663 | 7,062 | 3,601 |
| white | 10419 | 98.5 | 96.2 |
| other | 244 | 1.5 | 3.8 |
| χ 2 = 55.90 p = 0.0001 | |||
| Parity | 11,141 | 7062 | 4,079 |
| none | 4896 | 46.2 | 40.0 |
| 1–2 | 5566 | 49.0 | 51.7 |
| 3+ | 679 | 4.8 | 8.3 |
| χ 2 = 75.91 p = 0.0001 | |||
| Home mortgage/ownership | 11,214 | 7062 | 4,152 |
| Yes | 8392 | 80.8 | 64.7 |
| rented | 2822 | 19.2 | 35.3 |
| χ 2 = 390.11 p = 0.0001 | |||
| House crowding | 11,053 | 7062 | 3,991 |
| < = 0.5 | 4555 | 45.6 | 33.5 |
| >0.5–0.75 | 5783 | 49.6 | 57.1 |
| 0.75->1.0 | 715 | 4.8 | 9.4 |
| χ 2 = 211.28 p = 0.0001 | |||
| Parental education | 10,721 | 7062 | 3,659 |
| Degree | 1723 | 19.3 | 9.9 |
| A levels | 2808 | 27.9 | 22.8 |
| O levels | 2564 | 24.7 | 22.5 |
| Vocational/CSE | 3626 | 28.2 | 44.7 |
| χ 2 = 354.93 p = 0.0001 | |||
| Maternal Age | 11,974 | 7,062 | 4,912 |
| 15–19 | 535 | 2.8 | 6.9 |
| 20–29 | 7928 | 65.0 | 68.0 |
| 30–39 | 3371 | 31.2 | 23.8 |
| 40+ | 140 | 1.1 | 1.3 |
| χ 2 = 169.38 p = 0.0001 | |||
| Maternal smoking | 11279 | 7062 | 4217 |
| no smoker | 8545 | 80.0 | 68.6 |
| smoker | 2734 | 20.0 | 31.4 |
| χ 2 = 187.86 p<0.001 | |||
| Paternal smoking | 10542 | 7062 | 4217 |
| no smoker | 6798 | 68.1 | 57.2 |
| smoker | 3744 | 31.9 | 42.8 |
| χ 2 = 187.86 p<0.001 | |||
| Maternal regular drinking | 11,204 | 7,062 | 4142 |
| never | 5105 | 45.7 | 45.4 |
| <1 glass a week | 4370 | 40.1 | 37.2 |
| 1–6 a week | 1524 | 12.8 | 15.0 |
| 1+ pday | 205 | 1.5 | 2.5 |
| χ 2 = 29.01 p<0.001 | |||
| Maternal ‘binge’ patterns of drinking | 11,158 | 7062 | 4,096 |
| none | 9262 | 84.6 | 80.3 |
| 1–4 days | 1433 | 11.9 | 14.6 |
| 5–10 days | 223 | 1.8 | 2.4 |
| 10+ days | 240 | 1.8 | 2.7 |
| χ 2 = 38.35 p<0.001 | |||
| Paternal regular drinking | 8,379 | 7,062 | 1,317 |
| never | 374 | 3.9 | 7.4 |
| <1 glass a week | 2098 | 24.6 | 27.3 |
| 1–6 a week | 4268 | 51.8 | 46.4 |
| 1+ pday | 1639 | 19.7 | 18.9 |
| χ 2 = 39.44 p<0.001 | |||
| Paternal ‘binge’ patterns of drinking | 8,454 | 7,062 | 1,392 |
| none | 1496 | 17.5 | 18.5 |
| 1–4 days | 3189 | 37.7 | 38.1 |
| 5–10 days | 2153 | 25.7 | 24.4 |
| 10+ days | 1616 | 19.1 | 19.0 |
| χ 2 = 1.45 p = 0.694 | |||