Table B1.
An indirect test of independence: regressing the covariate on the instruments.
| Unweighted allelic score |
Weighted allelic score |
32 independent variants | |||
|---|---|---|---|---|---|
| Coefficient | Standard error | Coefficient | Standard error | p-Value of F-test: instrument-coefficients jointly equal to zero | |
| Girl | 0.00 | (0.00) | 0.00 | (0.01) | 0.560 |
| Birth weight (g) | 2.62 | (2.18) | 19.22 | (14.11) | 0.550 |
| Age at KS3 (in months) | 0.04*** | (0.02) | 0.16 | (0.10) | 0.341 |
| Ln(income) | 0.00 | (0.00) | 0.00 | (0.01) | 0.392 |
| Mother's education | −0.00 | (0.00) | −0.00 | (0.02) | 0.341 |
| Raised by natural father | 0.00 | (0.00) | 0.00 | (0.01) | 0.731 |
| Social class at birth | −0.00 | (0.01) | −0.03 | (0.03) | 0.076 |
| Mum works part-time | 0.00 | (0.00) | −0.01 | (0.01) | 0.971 |
| Mum works full-time | −0.00 | (0.00) | −0.00 | (0.01) | 0.428 |
| Partner employed | 0.00 | (0.00) | 0.01 | (0.01) | 0.905 |
| Index of Multiple Deprivation | −0.06 | (0.06) | 0.32 | (0.37) | 0.259 |
| Alcohol during pregnancy | 0.00 | (0.00) | 0.01 | (0.01) | 0.596 |
| Smoke during pregnancy | 0.00 | (0.00) | 0.00 | (0.01) | 0.697 |
| Breastfeeding | 0.00 | (0.00) | 0.00 | (0.03) | 0.080 |
| Mother's age at birth | 0.00 | (0.00) | −0.00 | (0.02) | 0.076 |
p < 0.01; The p-value in the last column corresponds to an F-test of the coefficients on the 32 instrumental variables jointly equalling zero; Ln(income) is measured when the child is aged 3–4 as is in 1995 prices; mother's educational level is a categorical variable with four values (less than ordinary (O) level, O-level, advanced (A) level, and university degree); social class is measured using the standard UK classification of class based on occupation (professional (I), managerial and technical (II), non-manual skilled (IIInm), manual skilled (IIIm), semi-skilled (IV) and unskilled (V)); the Index of Multiple Deprivation (IMD) is a measure of local area deprivation, measured at birth, referring to areas containing about 8000 persons; breastfeeding is a categorical variable (never, <1 month, 1–3 months and 3+ months); the sample contains 4846 observations.