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Response surface methods are types of Experimental Design that investigate the curvature of the response surface. They achieve this by using a quadratic regression equation rather than the linear form of the regression equation used in factorial designs.
When the response surface is approximated by a linear equation the maximum and minimum values always occur at a corner point. Thus it is not possible to use the regression equation to optimize the process if the true maximum or minimum lies within the interior of the response surface.
There are various types of response surface design including the Central Composite (CCD) and Box Behnken designs. CCD is a type of response surface design that has points at:
- the center
- the corner points
- axial points at 'a ' from the center
The design is usually rotatable, if the correct value of 'a' is selected.
A Box Behnken design is a type of response surface design that has points at:
- the center
- the midpoint of each side
There are no corner points. The design is spherical, all the points (except the center point) lie on a sphere of radius SQRT2.
For more information follow the link for Response Surface Methods in MiC Quality Six Sigma Glossary.
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