Hybrid Designs for Quadratic Response Surfaces

Abstract

Hybrid designs were created to achieve the same degree of orthogonality as central composite or regular polyhedral designs, to be near-minimum-point, and to be near-rotatable. They resemble central composite designs which have been augmented with at extra variable column. Eight designs are presented covering 3, 4, and 6 variables. All of these are at or within one point of minimum. Characteristics relevant to choice of design are discussed. Efliciencies are compared to central composite or polyhedral designs on n-spheres. A 46 point 7 variable design is also presented which, although it is not near-minimum, is an economical alternative to a 79 point central composite design.

Key Words:

• Second-Order Designs
• Orthogonality
• Rotatability
• D-Efficiency
• G-Efficiency