Defining Consistent Constraint Regions in Mixture Experiments

Physical, theoretical, and economic considerations in mixture experimentation often impose constraints on the levels of components in the mixture. These constraints define the region of interest and hence play an important role in the design and analysis of the mixture experiment. Because of this important role, sufficient care must be taken in developing the set of constraints. This article discusses several guidelines for developing mixture constraints and presents techniques for checking the consistency of the constraints developed. The guidelines and techniques are illustrated using several examples.