Slope rotatability over all directions designs

Abstract

Slope rotatability over all directions (SROAD)is a useful concept when the slope of a second-order response is to be studied. SROAD designs ensure that knowledge of the slope is acquired symmetrically, whatever direction later becomes of more interest as the data are analyzed. Some standard second-order designs are SROAD,but here we explore designs for two and three dimensions, which do not have the full symmetries of such standard designs but which still possess the SROAD property.