(* PS7.6, using DATA7-4, for the Application in Section 7.6 .  First
generate the interactions between D90 and the explanatory variables.
*)
genr D90YF = D90*YF
genr D90YM=D90*YM
genr D90EDUC=D90*EDUC
genr D90UE=D90*UE
genr D90MR=D90*MR
genr D90DR=D90*DR
genr D90URB=D90*URB
genr D90WH=D90*WH
list
(* Estimate the most general model *)
ols WLFP const D90 YF D90YF YM D90YM EDUC D90EDUC UE D90UE MR D90MR \
 DR D90DR URB D90URB WH D90WH 
(* omit variables one at a time *)
omit YM  
omit D90EDUC  
omit D90  
omit D90YM  
omit D90WH  
omit D90URB  
(* final model *)
omit D90DR  







