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Abstract
Split-plot designs are effective in industry due to time and/or cost constraints, restriction on randomization of the treatment combinations of the hard-to-change factors, and different sizes of experimental units. Some of the results of fractional factorial split-plot experiments can be ambiguous and a need may arise to conduct follow-up experiments to separate effects of potential interest by breaking their alias links with others. For completely randomized fractional factorial experiments, methods have been developed to construct follow-up experiments. In this article, we extend the foldover technique to break the alias chains of split-plot experiments. Because it is impractical or not economically possible to foldover the whole-plot factors, as their levels are often hard or expensive to change, the focus of this article is on folding over only one or more subplot factors in order to de-alias certain effects. Six rules are provided to develop foldovers for minimum aberration resolution III and resolution IV fractional factorial split-plot designs.
Additional information
Notes on contributors
Ashraf A. Almimi
Dr. Almimi is a Postdoctoral Research Fellow at the National Aeronautics and Space Administration's Langley Research Center. He is a Member of ASQ. His email address is [email protected].
Murat Kulahci
Dr. Kulahci is an Assistant Professor in the Department of Industrial Engineering at Arizona State University and an Associate Professor in Informatics and Mathematical Modeling at Technical University of Denmark. He is a Member of ASA. His email address is [email protected].
Douglas C. Montgomery
Dr. Montgomery is Regents' Professor of Industrial Engineering and Statistics in the Department of Industrial Engineering at Arizona State University. He is a Fellow of ASQ. His email address is [email protected].
