Models for the Response of a Mixture

SUMMARY Care needs to be exercised in the choice of model for a mixture system. The polynomial model, for example, cannot satisfactorily account for components which are inert or have additive effects and its coefficients lose their interpretative value when the variables are the proportions of components in the mixture. This paper proposes models constructed from functions homogeneous of degree one which overcome these difficulties, yet leave a wide choice of models.