person identifier
1980 to 1987
=1 if in agriculture
=1 if black
=1 if in construction
labor mkt experience
=1 if Hispanic
=1 if in poor health
annual hours worked
=1 if in manufacturing
=1 if married
=1 if north central
=1 if north east
=1 if south
years of schooling
=1 if in union
log(wage)
=1 if year == 1981
exper^2