# Exercise 3 - PS IV - Fertility
open fertility.gdt

# OLS 
ols weeksm1 const morekids --robust

# samesex and morekids
ols morekids const samesex --robust

# IV 
tsls weeksm1 const morekids; const samesex --robust

# Additional Regressors
tsls weeksm1 const morekids black hispan othrace; const black hispan othrace samesex --robust

# Hausman Test
ols morekids const samesex black hispan othrace --robust
genr u1 = $uhat

ols weeksm1 const morekids black hispan othrace u1 --robust