? P&R Exercise 11.3

options  crt;
options limwarn=0;
smpl 1 95;
read(file='ex113.xls', format=excel) yesvm tyear schl priv pub12 pub34 pub5 loginc logprice logeduc;
olsq  yesvm c priv pub12 pub34 pub5 tyear schl loginc logprice;
lsprob=@fit;
probit yesvm c priv pub12 pub34 pub5 tyear schl loginc logprice;
prprob=@fit;
logit yesvm c priv pub12 pub34 pub5 tyear schl loginc logprice;
loprob=@fit;
smpl 1 10;
print yesvm lsprob prprob loprob;
smpl 1 95;
olsq  logeduc c loginc logprice;
ystar=logeduc*yesvm;
olsq ystar c loginc logprice;
probit  yesvm c loginc logprice;
smplif yesvm;
olsq ystar c loginc logprice @mills;
end;stop;