Noncentral Composite Designs

Abstract

Second-order designs are constructed by adding a second two-level design to an initial 2^k or 2^k−p experiment. I label such designs as noncentral composite designs since they are composed of two designs with different centers. The location of the second block can be determined following analysis of the initial experiment. Noncentral composite designs provide an attractive alternative to the popular central composite designs when the location of interest shifts following an initial two-level design. An alternative family of asymmetric composite designs is also considered. The methodology is illustrated via a paper-helicopter experiment.

KEY WORDS :

• Asymmetric composite design
• Central composite design
• Fractional factorial
• Sequential experimentation
• Simplex design
• Steepest ascent