sysuse auto gen wgt=2 replace wgt=1 if foreign regress price mpg [pw=wgt] total wgt regress price mpg [fw=wgt] replace invp = wgt*74/126 regress price mpg [iw=invp] regress price mpg [pw=wgt] regress price [pw=wgt] regress price [iw=invp] summ price [iw=invp]