A-OPTIMAL DESIGNS FOR AN ADDITIVE QUADRATIC MIXTURE MODEL

Quadratic models are widely used in the analysis of experiments involv ing mixtures. This paper gives A-optimal designs for an additive quadr atic mixture model for q greater than or equal to 3 mixture components . It is proved that in these A-optimal designs, vertices of the simple x Sq-1 are support points, and other support points shift gradually fr om barycentres of depth 1 to barycentres of depth 3 as q increases. A- optimal designs with minimal support are also discussed.