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Main Authors: Gilmour, Steven G, Goos, Peter, Grossmann, Heiko
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2504.16531
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author Gilmour, Steven G
Goos, Peter
Grossmann, Heiko
author_facet Gilmour, Steven G
Goos, Peter
Grossmann, Heiko
contents Since the dawn of response surface methodology, it has been recommended that designs include replicate points, so that pure error estimates of variance can be obtained and used to provide unbiased estimated standard errors of the effects of factors. In designs with more than one stratum, such as split-plot and split-split-plot designs, it is less obvious how pure error estimates of the variance components should be obtained, and no pure error estimates are given by the popular residual maximum likelihood (REML) method of estimation. We propose a method of pure error REML estimation of the variance components, using the full treatment model, obtained by treating each combination of factor levels as a discrete treatment. Our method is easy to implement using standard software and improved estimated standard errors of the fixed effects estimates can be obtained by applying the Kenward-Roger correction based on the pure error REML estimates. We illustrate the new method using several data sets and compare the performance of pure error REML with the standard REML method. The results are comparable when the assumed response surface model is correct, but the new method is considerably more robust in the case of model misspecification.
format Preprint
id arxiv_https___arxiv_org_abs_2504_16531
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Pure Error REML for Analyzing Data from Multi-Stratum Designs
Gilmour, Steven G
Goos, Peter
Grossmann, Heiko
Methodology
Since the dawn of response surface methodology, it has been recommended that designs include replicate points, so that pure error estimates of variance can be obtained and used to provide unbiased estimated standard errors of the effects of factors. In designs with more than one stratum, such as split-plot and split-split-plot designs, it is less obvious how pure error estimates of the variance components should be obtained, and no pure error estimates are given by the popular residual maximum likelihood (REML) method of estimation. We propose a method of pure error REML estimation of the variance components, using the full treatment model, obtained by treating each combination of factor levels as a discrete treatment. Our method is easy to implement using standard software and improved estimated standard errors of the fixed effects estimates can be obtained by applying the Kenward-Roger correction based on the pure error REML estimates. We illustrate the new method using several data sets and compare the performance of pure error REML with the standard REML method. The results are comparable when the assumed response surface model is correct, but the new method is considerably more robust in the case of model misspecification.
title Pure Error REML for Analyzing Data from Multi-Stratum Designs
topic Methodology
url https://arxiv.org/abs/2504.16531