(* PS6.11 using DATA6-4 for Example 6.8 *)  
logs WAGE  
ols l_WAGE const EDUC EXPER AGE 
genr ut = uhat
square EDUC EXPER AGE  
ols ut const EDUC EXPER AGE sq_EDUC sq_EXPER sq_AGE  
genr LM = $nrsq
pvalue X 3 LM
