Design Of Experiments, Response Surface, Spline, Box Behnken, Central Composite Design.
you do not have to specify the exact function. PROC RSREG does this automatically. Comparison of both PROC RSREG results. In comparison to PROC GLIMMIX, we had to analyze separately per treatment group. And the contour plots. As you can see, they may not be that much of a curvilinear relationship