I want to estimate this equation y=a+b1*x+b2*x**(2) using gmm
When I write this program it does not work
proc model data= bb.mstylevw;
parms a b1 b2 ;
y=a+b1*x+b2 *x**(2);
fit y / gmm;
run;
quit;
when I remove Gmm, it works and it gives me regression using OLS
proc model data= bb.mstylevw;
parms a b1 b2 ;
y=a+b1*x+b2 *x**(2);
fit y / ;
run;
quit;