Small robust response-surface designs for quantitative and qualitative factors

Draper and John gave some specific response-surface designs for quantitative and qualitative factors. Wu and Ding gave a systematic method for constructing such designs. Aggarwal and Bansal gave robust response surface design for quantitative and qualitative factors using central composite designs. In this paper, we give a method for constructing robust response-surface designs for quantitative and qualitative factors using the small response-surface optimization approach given by Lin and Tu for finding the optimal setting for a set of design variables involving qualitative and quantitative factors.