View in EDS

Powerful Foldover Designs.

Saved in:
Bibliographic Details
Title: Powerful Foldover Designs.
Authors: Stallrich, Jonathan1 (AUTHOR) jwstalli@ncsu.edu, Singh, Rakhi2 (AUTHOR), Vogt‐Lowell, Kyle3 (AUTHOR), Li, Fanxing3 (AUTHOR)
Source: Quality & Reliability Engineering International. Oct2025, p1. 12p.
Subject Terms: *EXPERIMENTAL design, *DESIGN techniques, *PROCESS optimization, *RESPONSE surfaces (Statistics)
Abstract: ABSTRACT The foldover technique for screening designs is well‐known to guarantee zero aliasing of the main effect estimators with respect to two‐factor interactions and quadratic effects. It is a key feature of many popular response surface designs, including central composite designs, definitive screening designs, and most orthogonal, minimally aliased response surface designs. In this paper, we show that the foldover technique is even more powerful, because it produces degrees of freedom for a variance estimator that is independent of model selection. These degrees of freedom are characterized as either pure error or fake factor degrees of freedom. A fast design construction algorithm is presented that minimizes the expected confidence interval criterion to maximize the power of screening main effects. An augmented design and analysis method is also presented to avoid having too many degrees of freedom for estimating variance and to improve model selection performance for second‐order models. Simulation studies show that our new designs are at least as good as traditional designs when effect sparsity and hierarchy hold, but do significantly better when these effect principles do not hold. A real data example is given for a 20‐run experiment where optimization of ethylene concentration is performed by manipulating eight process parameters. [ABSTRACT FROM AUTHOR]
Database: Academic Search Index
Description
Abstract:ABSTRACT The foldover technique for screening designs is well‐known to guarantee zero aliasing of the main effect estimators with respect to two‐factor interactions and quadratic effects. It is a key feature of many popular response surface designs, including central composite designs, definitive screening designs, and most orthogonal, minimally aliased response surface designs. In this paper, we show that the foldover technique is even more powerful, because it produces degrees of freedom for a variance estimator that is independent of model selection. These degrees of freedom are characterized as either pure error or fake factor degrees of freedom. A fast design construction algorithm is presented that minimizes the expected confidence interval criterion to maximize the power of screening main effects. An augmented design and analysis method is also presented to avoid having too many degrees of freedom for estimating variance and to improve model selection performance for second‐order models. Simulation studies show that our new designs are at least as good as traditional designs when effect sparsity and hierarchy hold, but do significantly better when these effect principles do not hold. A real data example is given for a 20‐run experiment where optimization of ethylene concentration is performed by manipulating eight process parameters. [ABSTRACT FROM AUTHOR]
ISSN:07488017
DOI:10.1002/qre.70105