A comparison between the performances of double sampling X and variable sample size X charts

The double sampling (DS) X and variable sample size (VSS) X charts are very effective to detect small and moderate shifts in the process mean. Both charts are usually investigated under the assumption of known process parameters. However, the process parameters are commonly estimated from an in-c...

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Main Authors: Teoh, W.L, Liow, K.L., Michael C. Khoo, B., Yeong, W.C., Teh, S.Y.
Format: Article
Language:English
Published: Penerbit Universiti Kebangsaan Malaysia 2014
Online Access:http://journalarticle.ukm.my/8604/1/jqma-10-2-paper2.pdf
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author Teoh, W.L
Liow, K.L.
Michael C. Khoo, B.
Yeong, W.C.
Teh, S.Y.
author_facet Teoh, W.L
Liow, K.L.
Michael C. Khoo, B.
Yeong, W.C.
Teh, S.Y.
author_sort Teoh, W.L
collection UKM
description The double sampling (DS) X and variable sample size (VSS) X charts are very effective to detect small and moderate shifts in the process mean. Both charts are usually investigated under the assumption of known process parameters. However, the process parameters are commonly estimated from an in-control Phase-I dataset because they are usually unknown in practice. Therefore, both cases of known and estimated process parameters for the DS X and VSS X charts are considered in this paper. It is well known that the run length distribution of a control chart is highly skewed, especially when the process parameters are estimated and the process is in-control or slightly out-of-control. Interpretation based solely on a specific performance measure could be misleading. Thus, various performance measures need to be used to evaluate the properties of the control charts. Generally, the design of a control chart with estimated process parameters is proposed without comparing with other control charts. Accordingly, this paper focuses mainly on the comparison of the average run length (ARL), standard deviation of the run length (SDRL) and average sample size (ASS) between the DS X and VSS X charts with known and estimated process parameters. The ARL and SDRL results indicate that the DS X chart outperforms the VSS X chart for all ranges of shifts. However, the converse is true in terms of the ASS.
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spelling ukm.eprints-86042016-12-14T06:47:41Z http://journalarticle.ukm.my/8604/ A comparison between the performances of double sampling X and variable sample size X charts Teoh, W.L Liow, K.L. Michael C. Khoo, B. Yeong, W.C. Teh, S.Y. The double sampling (DS) X and variable sample size (VSS) X charts are very effective to detect small and moderate shifts in the process mean. Both charts are usually investigated under the assumption of known process parameters. However, the process parameters are commonly estimated from an in-control Phase-I dataset because they are usually unknown in practice. Therefore, both cases of known and estimated process parameters for the DS X and VSS X charts are considered in this paper. It is well known that the run length distribution of a control chart is highly skewed, especially when the process parameters are estimated and the process is in-control or slightly out-of-control. Interpretation based solely on a specific performance measure could be misleading. Thus, various performance measures need to be used to evaluate the properties of the control charts. Generally, the design of a control chart with estimated process parameters is proposed without comparing with other control charts. Accordingly, this paper focuses mainly on the comparison of the average run length (ARL), standard deviation of the run length (SDRL) and average sample size (ASS) between the DS X and VSS X charts with known and estimated process parameters. The ARL and SDRL results indicate that the DS X chart outperforms the VSS X chart for all ranges of shifts. However, the converse is true in terms of the ASS. Penerbit Universiti Kebangsaan Malaysia 2014-12 Article PeerReviewed application/pdf en http://journalarticle.ukm.my/8604/1/jqma-10-2-paper2.pdf Teoh, W.L and Liow, K.L. and Michael C. Khoo, B. and Yeong, W.C. and Teh, S.Y. (2014) A comparison between the performances of double sampling X and variable sample size X charts. Journal of Quality Measurement and Analysis, 10 (2). pp. 15-31. ISSN 1823-5670 http://www.ukm.my/jqma/jqma10_2a.html
spellingShingle Teoh, W.L
Liow, K.L.
Michael C. Khoo, B.
Yeong, W.C.
Teh, S.Y.
A comparison between the performances of double sampling X and variable sample size X charts
title A comparison between the performances of double sampling X and variable sample size X charts
title_full A comparison between the performances of double sampling X and variable sample size X charts
title_fullStr A comparison between the performances of double sampling X and variable sample size X charts
title_full_unstemmed A comparison between the performances of double sampling X and variable sample size X charts
title_short A comparison between the performances of double sampling X and variable sample size X charts
title_sort comparison between the performances of double sampling x and variable sample size x charts
url http://journalarticle.ukm.my/8604/1/jqma-10-2-paper2.pdf
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