Table 1.
Characteristics of the MCS across analytical samples
| Weighted % (observed n) unless indicated otherwise |
||||
|---|---|---|---|---|
| A. All children with accelerometer data (n = 6497) | B. Complete case (n=5615) | C. Analytical (imputed) sample (with M = 20) (n = 6493) | D. Original MCS sample (n = 18 981) | |
| Income quintile (measured at age 5 years) | ||||
| Highest (1) | 19 (1433) | 20 (1329) | 19 | 20 (2614) |
| 2 | 19 (1434) | 19 (1292) | 19 | 20 (2855) |
| 3 | 21 (1353) | 21 (1212) | 21 | 20 (2908) |
| 4 | 20 (1154) | 20 (996) | 20 | 20 (3209) |
| Lowest (5) | 21 (927) | 20 (786) | 22 | 20 (3346) |
| Not present at relevant sweep | n/a | n/a | n/a | 3940 |
| Item missing | 196 | n/a | n/a | 109 |
| Sex | ||||
| Male | 51 (3176) | 51 (2739) | 51 | 51 (9775) |
| Female | 49 (3321) | 49 (2876) | 49 | 49 (9206) |
| Not present at relevant sweep | n/a | n/a | n/a | n/a |
| Item missing | 0 | n/a | n/a | 0 |
| Baseline confounding (reported at age 9 months) | ||||
| Ethnicity | ||||
| White | 87 (5788) | 88 (5062) | 88 | 89 (15 730) |
| Mixed | 0·8 (41) | 0·8 (34) | 0·7 | 9·4 (195) |
| Indian | 2·0 (146) | 2·0 (124) | 1·9 | 1·9 (503) |
| Pakistani/Bangladeshi | 5·3 (253) | 4·7 (191) | 4·9 | 3·9 (1323) |
| Black or Black British | 3·2 (161) | 2·7 (124) | 2·9 | 2·7 (721) |
| Other | 1·6 (96) | 1·4 (80) | 1·4 | 1·6 (370) |
| Not present at relevant sweep | n/a | n/a | n/a | n/a |
| Item missing | 12 | n/a | n/a | 139 |
| Intermediate confounding (reported at age 5 years) | ||||
| Maternal BMI (mean, SE) | 25 (0·11) | 25 (0·11) | 25 (0·11) | 25 (0·07) |
| Not present at relevant sweep | n/a | n/a | n/a | 3940 |
| Item missing | 201 | n/a | n/a | 2518 |
| Regular bedtime? | ||||
| Never or almost never | 4·4 (243) | 3·8 (187) | 4·4 | 4·8 (760) |
| Sometimes | 5·2 (295) | 4·8 (240) | 5·2 | 5·1 (860) |
| Usually | 26 (1773) | 26 (1550) | 25·9 | 27 (4125) |
| Always | 65 (4137) | 65 (3638) | 64·5 | 63 (9227) |
| Not present at relevant sweep | n/a | n/a | n/a | 3940 |
| Item missing | 49 | n/a | n/a | 69 |
| Screen time daily | ||||
| < 1 h | 19 (1337) | 19 (1184) | 19 | 20 (2684) |
| 1-3 h | 65 (4205) | 65 (3647) | 65 | 65 (8748) |
| 3+ h | 16 (948) | 16 (784) | 16 | 15 (2173) |
| Not present at relevant sweep | n/a | n/a | n/a | 3940 |
| Item missing | 7 | n/a | n/a | 1436 |
| Physical activity (measured at age 7) | ||||
| dMVPA (median, SE) | 61 (0·42) | 61 (0·44) | 61 (0·42) | 61 (0·42) |
| Achieving 60 mins per day | 51 (3119) | 49 (2725) | 51 | 51 (3182) |
| Not present at relevant sweep | n/a | n/a | n/a | 5300 |
| Item missing | n/a | n/a | n/a | 7184 |
| BMI status (measured at age 11) | ||||
| Healthy | 74 (4543) | 74 (4305) | 73 | 71 (8319) |
| Overweight | 21 (1125) | 21 (1064) | 21 | 22 (2639) |
| Obese | 5·6 (270) | 5·4 (246) | 6·0 | 6·7 (806) |
| Not present at relevant sweep | n/a | n/a | n/a | 5869 |
| Item missing | 559 | n/a | n/a | 1348 |
| Variables for targeting interventions (reported at age 7 years) | ||||
| Area deprivation | ||||
| Most deprived quintile | 21 (1243) | 19 (998) | 22 | 22 (3573) |
| Not present at relevant sweep | n/a | n/a | n/a | 5300 |
| Item missing | 1 | 1 | n/a | 2 |
| Active travel to and from school | ||||
| No | 45 (3012) | 46 (2822) | 45 | 45 (6675) |
| One way | 3·4 (233) | 3·5 (206) | 3·4 | 3·4 (485) |
| Both ways | 52 (3012) | 51 (2580) | 52 | 52 (6432) |
| Not present at relevant sweep | n/a | n/a | n/a | 5300 |
| Item missing | 16 | 7 | n/a | 98 |
Column A, B: to account for sample design and inclusion in the physical activity (PA) study; column C: to account for sample design and inclusion in the PA study (since PA data were not imputed); column D: to account for sample design and attrition to relevant sweep.
PA, physical activity; dMVPA, moderate-to-vigorous physical activity; SE, standard error; M, number of imputed subsamples.