Efficient homogeneously weighted dispersion control charts with an application to distillation process

Monitoring disturbances in process dispersion using control chart is mostly based on the assumption that the quality characteristic follows normal distribution, which is not the case in many real‐life situations. This paper proposes a set of new dispersion charts based on the homogeneously weighted...

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Bibliographic Details
Published in:Quality and reliability engineering international 2021-12, Vol.37 (8), p.3221-3241
Main Authors: Abbasi, Saddam Akber, Nassar, Sara Hussam, Aldosari, Mashael Mohammed, Adeoti, Olatunde A.
Format: Article
Language:English
Subjects:
average run length
control chart
Control charts
Design parameters
Dispersion
Distillation
extra quadratic loss
HWMA
Normal distribution
process dispersion
Skewed distributions
Vapor pressure
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Summary:Monitoring disturbances in process dispersion using control chart is mostly based on the assumption that the quality characteristic follows normal distribution, which is not the case in many real‐life situations. This paper proposes a set of new dispersion charts based on the homogeneously weighted moving average (HWMA) scheme, for efficient detection of shifts in process standard deviation (σ). These charts are based on a variety of σ estimators and are investigated for normal as well as heavy tailed symmetric and skewed distributions. The shift detection ability of the charts is evaluated using different run length characteristics, such as average run length (ARL), extra quadratic loss (EQL), and relative ARL measures. The performance of the proposed HWMA control charts is also compared with the existing EWMA dispersion charts, using different design parameters. Furthermore, an illustrative example is presented to monitor the vapor pressure in a distillation process.
ISSN:0748-8017
1099-1638
DOI:10.1002/qre.2904