Table 4.
First stage specification tests of the instrumental variable regressions of child adiposity (fat mass).
| (1) Fat mass, age 11 |
(2) Fat mass, age 11 |
(3) Fat mass, age 11 |
|
|---|---|---|---|
| A. maternal BMI as IV | |||
| IV strength, F-statistic | 145.0 | 127.4 | 127.1 |
| Under identification LM testa | 229.8 | 210.0 | 209.7 |
| B. child's lagged fat mass as IV | |||
| IV strength, F-statistic | 1661.7 | 1513.8 | 1496.0 |
| Under identification LM testa | 746.7 | 740.0 | 744.7 |
| C. genetic markers as IV | |||
| IV strength, F-statistic | 16.0 | 20.2 | 19.1 |
| Under identification LM test a | 31.4 | 39.5 | 37.4 |
| Contextual variables | – | Yes | Yes |
| Mother's health and behaviour | – | – | Yes |
Notes: All controls included. Number of observations in all specifications is 3001.
a
The Kleibergen-Paap LM statistic for under-identification.