### Comparison to Other SAS Software

Other SAS/STAT procedures can be used to fit the response surface, but the RSREG procedure is more specialized. PROC RSREG
uses a much more compact model syntax than other procedures; for example, the following statements model a three-factor response
surface in the REG, GLM, and RSREG procedures:

proc reg;
model y=x1 x1*x1
x2 x1*x2 x2*x2
x3 x1*x3 x2*x3 x3*x3;
run;
proc glm;
model y=x1|x2|x3@2 x1*x1 x2*x2 x3*x3;
run;
proc rsreg;
model y=x1 x2 x3;
run;

Additionally, PROC RSREG includes specialized methodology for analyzing the fitted response surface, such as canonical analysis
and optimum response ridges.