pause on
use wage1
reg lwage educ exper
pause
reg lwage educ exper expersq
predict lwhat
pause
gen age=18+exper
scatter lwhat age if educ==12 
pause
clear
use airfare
reg lfare ldist
predict lfhat1
pause
reg lfare ldist ldistsq
pause
predict lfhat2
gen fhat1=exp(lfhat1)
gen fhat2=exp(lfhat2)
pause
scatter fhat1 dist
pause
scatter fhat2 dist