Title
An Improved Design Of Exponentially Weighted Moving Average Scheme For Monitoring Attributes
Abstract
The Exponentially Weighted Moving Average (EWMA) schemes are a potent tool for monitoring small to moderate variations in the quality characteristics in production lines of manufacturing industries. Practitioners in various sectors widely use the EWMA schemes for scrutinising both the variables and attributes. In the present article, we investigate a modified EWMA scheme based on the power of the difference between the actual number of nonconforming items and its technical specification in an in-control (IC) situation. We abbreviate it as a wEWMA scheme and show that the traditional EWMA scheme is a particular case of the proposed scheme when the power is unity. We establish that the powers lower than unity are more effective for detecting smaller shifts, while for detecting substantial variations in process parameter, one should prefer higher powers greater than unity. Noting that possible magnitude of a shift is often unknown, we propose the optimal design procedure of the scheme, including the determination of its charting parameters to ensure the best overall performance. The results reveal that the optimal wEWMA schemes can be beneficial in detecting a shift very quickly when the sample size is small, particularly for high-precision production processes.
Year
DOI
Venue
2020
10.1080/00207543.2019.1605224
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH
Keywords
DocType
Volume
attributes, average run length, number of defectives, quality control, process monitoring
Journal
58
Issue
ISSN
Citations 
3
0020-7543
0
PageRank 
References 
Authors
0.34
0
5
Name
Order
Citations
PageRank
Salah Haridy1192.89
Salah Haridy2192.89
Mohammad Shamsuzzaman300.68
Imad Alsyouf4115.44
A. Mukherjee54712.88