On Slope Rotatability of Central Composite Designs of the Second Type

  • Kim, Hyuk-Joo (Division of Mathematics and Informational Statistics and Institute of Basic Natural Sciences, Wonkwang University) ;
  • Ko, Yun-Mi (Department of Informational Statistics, Graduate School, Wonkwang University)
  • Published : 2004.04.01


Kim(2002) proposed a second type of central composite design (CCD2), in which the positions of the axial points are indicated by two numbers. In this paper, we study properties of CCD2 when we are interested in estimating the slope of a response surface. Conditions are obtained for CCD2 to be slope-rotatable over axial directions, and some CCD2's are presented that have slope rotatability over axial directions. Also values of a measure of slope rotatability over axial directions are tabulated for various CCD2's. Finally, it is shown that CCD2 is always slope-rotatable over all directions.


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