Comparisons of Alternative Axial Distances for Cuboidal Regions of Central Composite Designs Using D and G Efficiencies
Keywords:Axial Distances, Central Composite Design, D-Efficiency, G-Efficiency, Pythagorean Means
In this study, three axial distances are proposed as alternatives to the existing axial distances of the Central Composite Design (CCD) in cuboidal design regions with the aim of providing formidable alternatives to the existing axial distances of the CCD whose prediction properties are less extreme and more stable in the cuboidal design regions. The three alternative axial distances, namely the arithmetic, harmonic and geometric axial distances for cuboidal regions, were developed algebraically based on the concepts of the three Pythagorean means. The strengths and weaknesses of the alternative axial distances were validated by comparing their performances with the existing axial distances in the cuboidal regions. The D- and G-efficiencies are used for comparison. The cuboidal region shows that the three alternative axial distances are consistently better in terms of the D- and G-efficiencies
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