Abstract: Quadratic models are widely used in the analysis of experiments involving mixtures. This paper gives A-optimal designs for an additive quadratic mixture model for q≥3 mixture components. It is proved that in these A-optimal designs, vertices of the simplex S q-1 are support points, and other support points shift gradually from barycentres of depth 1 to barycentres of depth 3 as q increases. A-optimal designs with minimal support are also discussed.
Key words and phrases: Additive model, A-optimal design, experiments with mixtures.