Table 1. Characteristics of response, complete case, and imputed samplesa.
| Response sampleb | Complete case samplec, n = 1647 | Imputed sample, n = 5107 | ||
|---|---|---|---|---|
| N | M (SD) or % | M (SD) or % | M (SD) or % | |
| Outcomes, Y (Cognitive ability and academic achievement) | ||||
| PPVT | 4185 | 74.4 (5.2) | 75.2 (4.9) | 74.2 (5.2) |
| Matrix reasoning | 4180 | 10.7 (3.0) | 11.0 (3.0) | 10.7 (3.0) |
| ARS-Literacy | 3408 | 3.4 (0.8) | 3.5 (0.7) | 3.4 (0.8) |
| ARS-Numeracy | 3357 | 3.3 (0.8) | 3.5 (0.8) | 3.3 (0.8) |
| Exposures, X (Temperament) | ||||
| Reactivity | 3530 | 3.0 (1.0) | 2.9 (0.9) | 3.0 (0.9) |
| Approach | 3533 | 3.9 (1.0) | 4.0 (1.0) | 3.9 (1.0) |
| Persistence | 3532 | 4.3 (0.7) | 4.3 (0.7) | 4.3 (0.7) |
| Intermediate variable, M | ||||
| Parenting practices | 4385 | 11.8 (3.9) | 12.0 (3.8) | 11.7 (3.9) |
| Confounders of X-M or X-Y | ||||
| Mother’s highest education, % | ||||
| Tertiary | 1677 | 32.9 | 41.4 | 32.9 |
| Diploma/certificate | 1766 | 34.6 | 34.2 | 34.6 |
| Schooling only | 1656 | 32.5 | 24.4 | 32.5 |
| Hardship score | 5089 | 0.9 (1.3) | 0.7 (1.1) | 0.9 (1.3) |
| Housing tenure, rented or other, % | 5100 | 35.8 | 23.0 | 35.8 |
| Aboriginal or Torres Straits Islander, % | 5107 | 4.5 | 2.1 | 4.5 |
| Index of relative socio-economic disadvantage (IRSD) | 5107 | 1008.8 (60.2) | 1017.2 (57.2) | 1008.8 (60.2) |
| Child is male, % | 5107 | 51.1 | 48.5 | 51.1 |
| Birthweight for gestational age z-score | 4999 | 0.0 (1.1) | 0.1 (1.0) | 0.0 (1.1) |
| Duration of breast feeding, % | ||||
| Never breastfed | 420 | 9.2 | 5.8 | 9.2 |
| <1 month | 518 | 11.4 | 8.4 | 11.4 |
| <3 months | 473 | 10.4 | 8.7 | 10.3 |
| <6 months | 692 | 15.2 | 14.0 | 15.2 |
| 6 months or more | 2461 | 53.9 | 63.2 | 54.0 |
| Maternal age | 5106 | 31.0 (5.5) | 32.2 (4.6) | 31.0 (5.5) |
| Mother is born in Australia, % | 4997 | 80.0 | 83.0 | 79.4 |
| Mother’s psychological distress | 4308 | 4.4 (0.8) | 4.5 (0.5) | 4.4 (0.6) |
| Mother and partner argumentative relationship | 3931 | 2.2 (0.6) | 2.1 (0.6) | 2.2 (0.6) |
| Single-parent household, % | 5103 | 9.7 | 0.2 | 9.7 |
| Mother had gestational hypertension, % | 4238 | 7.8 | 7.8 | 8.1 |
| Mother had gestational diabetes, % | 4223 | 5.7 | 5.2 | 5.9 |
| Any alcohol during pregnancy, % | 4227 | 38.9 | 44.1 | 37.3 |
| Smoking during pregnancy, % | 4239 | 16.7 | 10.6 | 18.2 |
| Confounders of M-Y | ||||
| Mother’s psychological distress | 3818 | 4.5 (0.6) | 4.5 (0.5) | 4.5 (0.6) |
| Number of siblings | 4386 | 1.5 (1.3) | 1.5 (0.9) | 1.5 (1.0) |
| Mother’s working status, % | ||||
| Working full-time | 957 | 21.8 | 19.8 | 21.1 |
| Working part-time | 1804 | 41.2 | 46.6 | 40.7 |
| Currently not working | 1622 | 37.0 | 33.6 | 38.2 |
| Household income per week, $ | 3668 | 1977.8 (1343.4) | 2054.5 (1365.3) | 1893.6 (1297.7) |
| Hardship score | 4365 | 0.3 (0.7) | 0.2 (0.6) | 0.3 (0.8) |
a Abbreviations: N, sample number; M(SD), mean (standard deviation); Y, outcomes; PPVT, Peabody Picture Vocabulary Test; ARS, Academic Rating Scale; X, exposures; M, mediators; X-M, exposure-mediator; X-Y, exposure-outcome; IRSD, index of relative socioeconomic disadvantage; M-Y, mediator-outcome
b Response sample is the number of participants who responded to specific assessment for each child exposure, outcome, or confounder,
cComplete case sample are participants who have data for every variable (i.e. no missing on any variable.