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Journal ArticleDOI: 10.1080/16843703.2020.1827726

Nonparametric progressive sign chart for monitoring process location based on individual data

04 Mar 2021-Quality Technology and Quantitative Management (Informa UK Limited)-Vol. 18, Iss: 2, pp 225-247
Abstract: Statistical process control (SPC) plays a vital role in the maintenances and improvements of quality outputs in manufacturing, industrial and service production processes. Control chart is an impor...

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Topics: Chart (62%), Statistical process control (60%), Control chart (56%)
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Open accessJournal Article
Abstract: Nonparametric control charts can provide a robust alternative in practice to the data analyst when there is a lack of knowledge about the underlying distribution. A nonparametric exponentially weighted moving average (NPEWMA) control chart combines the advantages of a nonparametric control chart with the better shift detection properties of a traditional EWMA chart. A NPEWMA chart for the median of a symmetric continuous distribution was introduced by Amin and Searcy (1991) using the Wilcoxon signed-rank statistic (see Gibbons and Chakraborti, 2003). This is called the nonparametric exponentially weighted moving average Signed-Rank (NPEWMA-SR) chart. However, important questions remained unanswered regarding the practical implementation as well as the performance of this chart. In this paper we address these issues with a more in-depth study of the two-sided NPEWMA-SR chart. A Markov chain approach is used to compute the run-length distribution and the associated performance characteristics. Detailed guidelines and recommendations for selecting the chart's design parameters for practical implementation are provided along with illustrative examples. An extensive simulation study is done on the performance of the chart including a detailed comparison with a number of existing control charts, including the traditional EWMA chart for subgroup averages and some nonparametric charts i.e. runs-rules enhanced Shewhart-type SR charts and the NPEWMA chart based on signs. Results show that the NPEWMA-SR chart performs just as well as and in some cases better than the competitors. A summary and some concluding remarks are given.

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Topics: Rank (graph theory) (60%), Chart (55%), Moving average (54%)

4 Citations


Journal ArticleDOI: 10.1080/03610918.2021.1910299
Zameer Abbas, Hafiz Zafar Nazir1, Muhammad Riaz2, Muhammad Abid3  +1 moreInstitutions (3)
Abstract: A control chart has become a choice of quality practitioners for monitoring the output of industrial and production processes. It is a common practice to develop control charts under normality assu...

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Topics: Chart (63%), Control chart (58%)

4 Citations



Journal ArticleDOI: 10.1007/S13369-021-05801-6
Saber Ali1, Zameer Abbas, Hafiz Zafar Nazir2, Muhammad Riaz3  +2 moreInstitutions (3)
Abstract: Efficient control charts are used to maintain and improve the manufacturing, industrial and service processes. Control chart is a basic tool of quality practitioners for producing products that meet market requirements in terms of quality, reliability and functionality. Lack of normality is a common occurrence in these processes. In such situations, distribution-free control charts are increasingly used for process monitoring. The nonparametric exponentially weighted moving average chart is a frequently used memory-type control chart in the process monitoring. The drawback of this chart is that it performs efficiently only on smaller values of the smoothing parameter. To compensate this drawback, a modified nonparametric exponentially weighted moving average chart under progressive setup based on sign and arcsine test statistics is proposed in this study. The prominent quality of the proposed scheme is that it performs efficiently in detecting small and persistent shifts in the process location under each choice of the smoothing parameter. The performance of the proposed chart has been investigated through simulations that use run length profiles (average run length, median run length and standard deviation of run length). When the performance of the proposed chart is compared with alternatives, its ability to detect small and persistent shifts is much better. Two real-life applications associated with hard-bake and piston rings manufacturing processes are included that show the demonstration of the proposed charts.

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Topics: Chart (68%), Control chart (62%), Smoothing (52%)

2 Citations


References
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43 results found


Journal ArticleDOI: 10.1093/BIOMET/41.1-2.100
E. S. Page1Institutions (1)
01 Jun 1954-Biometrika

4,393 Citations



Journal ArticleDOI: 10.1080/00224065.1999.11979944
Abstract: An overview is given of current research on control charting methods for process monitoring and improvement. A historical perspective and ideas for future research also are given. Research topics include: variable sample size and sampling interval met..

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616 Citations


Journal ArticleDOI: 10.1080/00224065.1999.11979900
Abstract: A control chart is considered for the problem of monitoring a process when all items from the process are inspected and classified into one of two categories. The objective is to detect changes in the proportion, p, of items in the first category. The c..

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Topics: Shewhart individuals control chart (60%), np-chart (55%), EWMA chart (55%) ... read more

180 Citations


Journal ArticleDOI: 10.2307/1269074
01 Aug 1986-Technometrics
Abstract: A new two-sided cumulative sum quality control scheme is proposed. The new scheme was developed specifically to be generalized to a multivariate cumulative sum quality control scheme. The multivariate version will be examined in a subsequent paper; this article evaluates the univariate version. A comparison of the conventional two-sided cumulative sum scheme and the proposed scheme indicates that the new scheme has slightly better properties (ratio of on-aim to off-aim average run lengths) than the conventional scheme. Steady state average run lengths are discussed. The new scheme and the conventional two-sided cumulative sum scheme have equivalent steady state average run lengths. Methods for implementing the fast initial response feature for the new cumulative sum scheme are given. A comparison of average run lengths for the conventional and proposed schemes with fast initial response features is also favorable to the new scheme. A Markov chain approximation is used to calculate the average run lengths ...

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157 Citations