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Journal ArticleDOI

X̄ charts with variable sample size

01 Jul 1994-Journal of Quality Technology (ASQ)-Vol. 26, Iss: 3, pp 155-163
TL;DR: In this article, the authors considered the properties of the X chart when the size of each sample depends on what is observed in the preceding hours and the usual practice in using a control chart to monitor a process is to take samples of size n from the process every h hours.
Abstract: The usual practice in using a control chart to monitor a process is to take samples of size n from the process every h hours. This article considers the properties of the X chart when the size of each sample depends on what is observed in the preceding ..
Citations
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Journal ArticleDOI
TL;DR: In this article, the control chart limits are calculated using parameter estimates from an in-control Phase I reference sample, and statistics based on new samples are compared with the estimated control limits to monitor for departures from the in..
Abstract: Control chart limits are often calculated using parameter estimates from an in-control Phase I reference sample. In Phase II monitoring, statistics based on new samples are compared with the estimated control limits to monitor for departures from the in..

532 citations

Journal ArticleDOI
TL;DR: In this paper, a combine X control chart is proposed, where the process control engineer waits until the control scheme signals an out-of-control condition, and then the process can be restarted.
Abstract: A conventional X control chart works in an open loop manner. That is, the process control engineer waits until the control scheme signals an out-of-control condition. This paper proposes a combine...

240 citations

Journal ArticleDOI
TL;DR: In this paper, a survey of recent developments in the statistical and economic design of adaptive or dynamic charts that allow some of their parameters to change is presented, in a comprehensive way.
Abstract: This survey presents, in a comprehensive way, the substantial recent developments in the statistical and economic design of adaptive or dynamic charts that allow some of their parameters to change ...

239 citations

Journal ArticleDOI
TL;DR: In this article, the X-bar chart with variable sampling intervals (VSI) and the variable sample size (VSS) are compared to the traditional X-Bar chart in detecting shifts in the process.
Abstract: Recent theoretical studies have shown that the X-bar chart with variable sampling intervals (VSI) and the X-bar chart with variable sample size (VSS) are quicker than the traditional X-bar chart in detecting shifts in the process. This article considers..

204 citations

Journal ArticleDOI
TL;DR: This paper extends the study of the X chart with variable parameters to include variable action limits, and presents a meta-analyses of the response of the immune system to these limits.
Abstract: Varying the parameters of the X chart has been explored extensively in recent years. In this paper, we extend the study of the X chart with variable parameters to include variable action limits. ...

166 citations

References
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Journal ArticleDOI
TL;DR: The variable sampling interval (VSI) chart as discussed by the authors uses a short sampling interval if the sample is close to but not actually outside the control limits, and a long sampling interval for the sample if it is closer to target.
Abstract: The usual practice in using a control chart to monitor a process is to take samples from the process with fixed sampling intervals. This article considers the properties of the chart when the sampling interval between each pair of samples is not fixed but rather depends on what is observed in the first sample. The idea is that the time interval until the next sample should be short if a sample shows some indication of a change in the process and long if there is no indication of a change. The proposed variable sampling interval (VSI) chart uses a short sampling interval if is close to but not actually outside the control limits and a long sampling interval if is close to target. If is actually outside the control limits, then the chart signals in the same way as the standard fixed sampling interval (FSI) chart. Properties such as the average time to signal and the average number of samples to signal are evaluated. Comparisons between the FSI and the VSI charts indicate that the VSI chart is substantially ...

473 citations

Journal ArticleDOI
James M. Lucas1
TL;DR: The SheWhart-CUSUM quality control scheme which combines the key features of the Shewhart and CUSUM control procedures is described and evaluated.
Abstract: The Shewhart-CUSUM quality control scheme which combines the key features of the Shewhart and CUSUM control procedures is described and evaluated. In this scheme the CUSUM feature will quickly detect small shifts from the goal while the addition of Shew..

412 citations

Journal ArticleDOI
TL;DR: In this paper, a combine X control chart is proposed, where the process control engineer waits until the control scheme signals an out-of-control condition, and then the process can be restarted.
Abstract: A conventional X control chart works in an open loop manner. That is, the process control engineer waits until the control scheme signals an out-of-control condition. This paper proposes a combine...

240 citations

Journal Article
TL;DR: In this article, the double sampling X chart is proposed, which is the counterpart to double sampling plans, which offers better statistical efficiency (in terms of statistical efficiency) than double sampling plan.
Abstract: The purpose of this paper is to propose a new control chart, the double sampling X chart, which is the counterpart to double sampling plans. This procedure offers better statistical efficiency (in...

190 citations

Journal ArticleDOI
TL;DR: The purpose of this paper is to propose a new control chart, the double sampling X chart, which is the counterpart to double sampling plans, which offers better statistical efficiency.
Abstract: The purpose of this paper is to propose a new control chart, the double sampling X chart, which is the counterpart to double sampling plans. This procedure offers better statistical efficiency (in...

186 citations