An improved variable sample size and sampling interval S control chart

Michael B. C. Khoo, May Yen See, Nger Ling Chong, Wei Lin Teoh

Research output: Contribution to journalArticle

Abstract

The standard deviation chart (S chart) is used to monitor process variability. This paper proposes an upper-sided improved variable sample size and sampling interval (VSSIt) S chart by improving the existing upper-sided variable sample size and sampling interval (VSSI) S chart through the inclusion of an additional sampling interval. The optimal designs of the VSSIt S chart together with the competing charts under consideration, such as the VSSI S and exponentially weighted moving average (EWMA) S charts, by minimizing the out-of-control average time to signal (ATS1) and expected average time to signal (EATS1) criteria, are performed using the MATLAB programs. The performances of the standard S, VSSI S, EWMA S, and VSSIt S charts are compared, in terms of the ATS1 and EATS1 criteria, where the results show that the VSSIt S chart surpasses the other charts in detecting moderate and large shifts, while the EWMA S is the best performing chart in detecting small shifts. An illustrative example is given to explain the implementation of the VSSIt S chart.

LanguageEnglish
Pages392-404
Number of pages13
JournalQuality and Reliability Engineering International
Volume35
Issue number1
Early online date17 Oct 2018
DOIs
Publication statusPublished - Feb 2019

Fingerprint

Sampling
Control charts
Sample size
Charts
MATLAB
Standard deviation
Exponentially weighted moving average

Keywords

  • average time to signal
  • control chart
  • expected average time to signal
  • process variability
  • variable sample size and sampling interval

ASJC Scopus subject areas

  • Safety, Risk, Reliability and Quality
  • Management Science and Operations Research

Cite this

Khoo, Michael B. C. ; See, May Yen ; Chong, Nger Ling ; Teoh, Wei Lin. / An improved variable sample size and sampling interval S control chart. In: Quality and Reliability Engineering International. 2019 ; Vol. 35, No. 1. pp. 392-404.
@article{243445f0d33e47cd9ebd4486f301d3c1,
title = "An improved variable sample size and sampling interval S control chart",
abstract = "The standard deviation chart (S chart) is used to monitor process variability. This paper proposes an upper-sided improved variable sample size and sampling interval (VSSIt) S chart by improving the existing upper-sided variable sample size and sampling interval (VSSI) S chart through the inclusion of an additional sampling interval. The optimal designs of the VSSIt S chart together with the competing charts under consideration, such as the VSSI S and exponentially weighted moving average (EWMA) S charts, by minimizing the out-of-control average time to signal (ATS1) and expected average time to signal (EATS1) criteria, are performed using the MATLAB programs. The performances of the standard S, VSSI S, EWMA S, and VSSIt S charts are compared, in terms of the ATS1 and EATS1 criteria, where the results show that the VSSIt S chart surpasses the other charts in detecting moderate and large shifts, while the EWMA S is the best performing chart in detecting small shifts. An illustrative example is given to explain the implementation of the VSSIt S chart.",
keywords = "average time to signal, control chart, expected average time to signal, process variability, variable sample size and sampling interval",
author = "Khoo, {Michael B. C.} and See, {May Yen} and Chong, {Nger Ling} and Teoh, {Wei Lin}",
year = "2019",
month = "2",
doi = "10.1002/qre.2407",
language = "English",
volume = "35",
pages = "392--404",
journal = "Quality and Reliability Engineering International",
issn = "0748-8017",
publisher = "John Wiley and Sons Ltd",
number = "1",

}

An improved variable sample size and sampling interval S control chart. / Khoo, Michael B. C.; See, May Yen; Chong, Nger Ling; Teoh, Wei Lin.

In: Quality and Reliability Engineering International, Vol. 35, No. 1, 02.2019, p. 392-404.

Research output: Contribution to journalArticle

TY - JOUR

T1 - An improved variable sample size and sampling interval S control chart

AU - Khoo, Michael B. C.

AU - See, May Yen

AU - Chong, Nger Ling

AU - Teoh, Wei Lin

PY - 2019/2

Y1 - 2019/2

N2 - The standard deviation chart (S chart) is used to monitor process variability. This paper proposes an upper-sided improved variable sample size and sampling interval (VSSIt) S chart by improving the existing upper-sided variable sample size and sampling interval (VSSI) S chart through the inclusion of an additional sampling interval. The optimal designs of the VSSIt S chart together with the competing charts under consideration, such as the VSSI S and exponentially weighted moving average (EWMA) S charts, by minimizing the out-of-control average time to signal (ATS1) and expected average time to signal (EATS1) criteria, are performed using the MATLAB programs. The performances of the standard S, VSSI S, EWMA S, and VSSIt S charts are compared, in terms of the ATS1 and EATS1 criteria, where the results show that the VSSIt S chart surpasses the other charts in detecting moderate and large shifts, while the EWMA S is the best performing chart in detecting small shifts. An illustrative example is given to explain the implementation of the VSSIt S chart.

AB - The standard deviation chart (S chart) is used to monitor process variability. This paper proposes an upper-sided improved variable sample size and sampling interval (VSSIt) S chart by improving the existing upper-sided variable sample size and sampling interval (VSSI) S chart through the inclusion of an additional sampling interval. The optimal designs of the VSSIt S chart together with the competing charts under consideration, such as the VSSI S and exponentially weighted moving average (EWMA) S charts, by minimizing the out-of-control average time to signal (ATS1) and expected average time to signal (EATS1) criteria, are performed using the MATLAB programs. The performances of the standard S, VSSI S, EWMA S, and VSSIt S charts are compared, in terms of the ATS1 and EATS1 criteria, where the results show that the VSSIt S chart surpasses the other charts in detecting moderate and large shifts, while the EWMA S is the best performing chart in detecting small shifts. An illustrative example is given to explain the implementation of the VSSIt S chart.

KW - average time to signal

KW - control chart

KW - expected average time to signal

KW - process variability

KW - variable sample size and sampling interval

UR - http://www.scopus.com/inward/record.url?scp=85055158503&partnerID=8YFLogxK

U2 - 10.1002/qre.2407

DO - 10.1002/qre.2407

M3 - Article

VL - 35

SP - 392

EP - 404

JO - Quality and Reliability Engineering International

T2 - Quality and Reliability Engineering International

JF - Quality and Reliability Engineering International

SN - 0748-8017

IS - 1

ER -