# Replicate the results in Table 15.1, p. 520 of Wooldridge
# This is relevant to Problem C15.3 on page 540.

open card.gdt -q

# We need a couple of transformed variables
series lwage = log(wage)
series expersq = exper^2

# Create list of regional dummy variables, dropping one
list reglist = reg66*
reglist -= reg661

# Build full list of regressors, apart from educ
list X = exper expersq black south smsa* reglist

# Try plain OLS estimation
ols lwage 0 educ X

# Try Two Stage Least Squares, treating educ as
# endogenous and using nearc4 as instrument
tsls lwage 0 educ X ; 0 nearc4 X