The Simplex-Centroid Design for Experiments with Mixtures

SUMMARY A new design for experiments with mixtures of q components comprises the 2q − 1 points representing the mixtures consisting of all possible subsets of the q components, present in equal proportions. A suitable regression equation is proposed and fitted. Designs and regression equations permitting the introduction of n “process variables” in addition to the q “mixture variables” are considered, and fractional replication of the designs in the case where the process variables are all at two levels.