Title: Monitoring Nonlinear Profiles with Random Effects by Nonparametric Regression
Authors: Shiau, Jyh-Jen Horng
Huang, Hsiang-Ling
Lin, Shuo-Hui
Tsai, Ming-Ye
Institute of Statistics
Keywords: Average run length;Control charts;Nonlinear profile monitoring;Principal components analysis;Profile-to-profile variation;Spline smoothing
Issue Date: 2009
Abstract: The monitoring of process/product profiles is presently a growing and promising area of research in statistical process control. This study is aimed at developing monitoring schemes for nonlinear profiles with random effects. We utilize the technique of principal components analysis to analyze the covariance structure of the profiles and propose monitoring schemes based on principal component ( PC) scores. The number of the PC scores used in constructing control charts is crucial to the detecting power. In the Phase I analysis of historical data, due to the dependency of the PC-scores, we adopt the usual Hotelling T(2) chart to check the stability. For Phase II monitoring, we study individual PC-score control charts, a combined chart scheme that combines all the PC-score charts, and a T(2) chart. Although an individual PC-score chart may be perfect for monitoring a particular mode of variation, a chart that can detect general shifts, such as the T(2) chart and the combined chart scheme, is more feasible in practice. The performances of the schemes under study are evaluated in terms of the average run length.
URI: http://hdl.handle.net/11536/7819
ISSN: 0361-0926
DOI: 10.1080/03610920802702535
Volume: 38
Issue: 10
Begin Page: 1664
End Page: 1679
Appears in Collections:Conferences Paper

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