### On comparing the prediction variances of some central composite designs in spherical regions: a review

CHIGBU, POLYCARP E.; Department Of Statistics-University Of Nigeria, Nsukka, UKAEGBU, EUGENE C.; Department Of Statistics-University Of Nigeria, Nsukka & NWANYA, JULIUS C.; Department Of Statistics-University Of Nigeria, Nsukka
Three second-order response surface designs, namely: central composite design, small composite design and minimum-run resolution V design are compared for factors 3 to 7 in spherical regions using the G- and I- optimality criteria. The structures of the response variances of the designs are displayed graphically using the variance dispersion graphs. The maximum and average response variances are determined analytical as functions of the radii of the design region. Results for the G- and I-...