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Στουραΐτη, Δανάη

Control charts for monitoring processvariability

Master Thesis

Author

Στουραΐτη, Δανάη

Date

2023-03

Abstract

Shewhart control charts are a significant and powerful tools in an attempt towards a more stable production process. Through these charts, possible deviations on various product parameters can be controlled, which if not identified on time, could possibly lead to an out of control process. Effective use of Shewhart control charts results in the production of optimum quality products and minimize the production of non-conforming ones. Usually, two types of control charts are compiled. One chart for monitoring the process mean and one for monitoring the process variability. Monitoring the process variability has gained the interest of several scientists the past decades. The present thesis is divided into three chapters. The first chapter describes control charts for monitoring the mean value and variability of a process. In addition the average run length is presented as well as the mean and variability estimates used in the control charts. In the second chapter the Shewhart R and S control charts with both 3σ control limits and probability limits are extensively studied. A comparison is made of the effectiveness of R and S control charts for monitoring the variability of a process for various sample sizes and various standard deviations. Finally, in the third chapter of this thesis, the CUSUM-S2 , CUSUM-lnS^2 , EWMA-S^2 and EWMA-lnS^2 charts are studied. Also, all control charts are compared with the average run length and conclusions are drawn as to which chart excels at small and large standard deviation shifts.

Postgraduate Studies Programme

Εφαρμοσμένη Στατιστική

Department

Σχολή Χρηματοοικονομικής και Στατιστικής. Τμήμα Στατιστικής και Ασφαλιστικής Επιστήμης

Number of pages

Language

Greek

URI

https://dione.lib.unipi.gr/xmlui/handle/unipi/15348
http://dx.doi.org/10.26267/unipi_dione/2770

Collections

Τμήμα Στατιστικής και Ασφαλιστικής Επιστήμης

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Except where otherwise noted, this item's license is described as
Αναφορά Δημιουργού-Μη Εμπορική Χρήση-Όχι Παράγωγα Έργα 3.0 Ελλάδα