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Classes of Split‐plot Response Surface Designs for Equivalent Estimation
Author(s) -
Parker Peter A.,
Kowalski Scott M.,
Vining G. Geoffrey
Publication year - 2006
Publication title -
quality and reliability engineering international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 62
eISSN - 1099-1638
pISSN - 0748-8017
DOI - 10.1002/qre.771
Subject(s) - restricted randomization , estimator , plot (graphics) , extension (predicate logic) , algorithm , property (philosophy) , computer science , mathematical optimization , split plot , context (archaeology) , design of experiments , mathematics , ordinary least squares , box–behnken design , response surface methodology , statistics , randomization , medicine , randomized block design , paleontology , philosophy , surgery , programming language , biology , randomized controlled trial , epistemology
When planning an experimental investigation, we are frequently faced with factors that are difficult or time consuming to manipulate, thereby making complete randomization impractical. A split‐plot structure differentiates between the experimental units associated with these hard‐to‐change factors and those that are relatively easy‐to‐change. Furthermore, it provides an efficient strategy that integrates the restrictions imposed by the experimental apparatus into the design structure. In this paper, several industrial and scientific examples are presented to highlight design considerations when a restriction on randomization is encountered. We propose classes of split‐plot response designs that provide an intuitive and natural extension from the completely randomized context. For these designs, the ordinary least‐squares estimates of the model are equivalent to the generalized least‐squares estimates. This property provides best linear unbiased estimators and simplifies model estimation. The design conditions that provide equivalent estimation are presented and lead to design construction strategies to transform completely randomized Box–Behnken, equiradial and small composite designs into a split‐plot structure. Published in 2006 by John Wiley & Sons, Ltd.