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Practical Inference from Industrial Split-Plot Designs

Summary: [This abstract is based on the authors' abstract.]When factors are not reset independently in industrial response surface experiments, the observations in the resulting split-plot experimental design are often correlated. Often the data is analyzed as if the experiment was completely randomized and the model is estimated using ordinary least squares. A proper analysis of the experimental data requires a mixed model analysis involving generalized least-squares estimation. The differences in conclusions reach from the two methods are quantified to provide guidance for analyzing split-plot experiments in practice. Determination of denominator degrees of freedom for significant tests in mixed model analysis is also discussed.

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  • Topics:
  • Keywords: Degrees of freedom,Least squares,Residual analysis,Response surface methodology (RSM),Split-plot design
  • Author: Goos, Peter; Langhans, Ivan; Vandebroek, Martina
  • Journal: Journal of Quality Technology