Factor Screening and Response Surface Exploration

Standard practice in response surface methodology performs factor screening and response surface exploration sequentially, using different designs. A novel approach is proposed to achieve the two objectives on the same experiment, based on one design. Running a uni-stage experiment has the advantages of saving experimentation time and run size. The approach is based on a two-stage analysis that employs factor screening, projection and response surface exploration. Projection-efficiency criteria are defined to evaluate the performance of the projected designs. The projection-efficiency properties of the 3n−k designs and three nonregular designs are studied, and comparisons with central composite designs are made. Nonregular designs appear to enjoy better projection properties. The strategy is illustrated with the analysis of a PVC insulation experiment.