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An EWMA mean chart with auxiliary information
Quality and Reliability Engineering International, 2023AbstractIn this paper, we show that a recently proposed auxiliary information‐based (AIB) adaptive EWMA (AE) chart is sensitive (not robust) to the changes in the mean of an auxiliary variable when monitoring the changes in the mean of a quality variable, called the AIB‐AE chart.
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Analysis of the Effects of Truncation on the EWMA Observer
2007 IEEE International Conference on Automation Science and Engineering, 2007For many years the exponentially weighted moving average (EWMA) observer has been used in practice for advanced process control (APC) in the semiconductor industry. A common practice is to truncate the length of data used in creating an EWMA estimate of the system state.
Martin W. Braun, Nital S. Patel
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The EWMA Patient Outcome Group
Journal of Wound Care, 2009Across Europe, clinical experts in wound care and industry representatives have joined forces to propose recommendations for clinical data collection on chronic wound management. Here, the chair of the group, Finn Gottrup, outlines its main objectives
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A Multivariate Sign EWMA Control Chart
Technometrics, 2011Nonparametric control charts are useful in statistical process control (SPC) when there is a lack of or limited knowledge about the underlying process distribution, especially when the process measurement is multivariate. This article develops a new multivariate SPC methodology for monitoring location parameters.
Changliang Zou, Fugee Tsung
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PBS machine interlocks using EWMA
Physics in Medicine and Biology, 2015Delivery of pencil beam scanning (PBS) requires the on-line measurement of several beam parameters. If the measurement is outside of specified tolerances and a binary threshold algorithm is used, the beam will be paused. Given instrumentation and statistical noise such a system can lead to many pauses which could increase the treatment time ...
Benjamin M, Clasie +2 more
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A Spatial‐EWMA Framework for Detecting Clustering
Quality and Reliability Engineering International, 2013Spatial surveillance is critical to health systems, manufacturing industries, and in many other domains. For example, determining hotspots of infectious diseases and detecting defect patterns on semiconductor wafers require sensitive spatial analysis tools. The goal of this paper is to detect spatial clusters with mean shifts. Conventional multivariate
Chen-ju Lin +2 more
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The EWMA median chart with estimated parameters
IIE Transactions, 2015ABSTRACTThe usual practice in control charts is to assume that the chart parameters are known or can be accurately estimated from in-control historical samples and the data are free from outliers. Both of these assumptions are not realistic in practice: a control chart may involve the estimation of process parameters from a very limited number of ...
Castagliola, Philippe +2 more
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Design and investigation of EWMA and double EWMA with quadratic process model in R2R controllers
Quality & Quantity, 2007In the last few years, “Run-to-Run” (R2R) control techniques have been developed and used to control various processes in industries. These techniques combine control engineering and statistical process control techniques. The R2R controller is basically consists of a linear regression model that relates the input variables to the output variables ...
R. B. Kazemzadeh +2 more
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2002
A problem with the conventional Shewhart charts is that the decisions are usually based on single observations. Such decision implies a high probability of false alarms. Also, small shifts in the process characteristics, which are of increasing importance from the point of view of efforts for continuous quality improvement, cannot be detected easily ...
M. Xie, T. N. Goh, V. Kuralmani
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A problem with the conventional Shewhart charts is that the decisions are usually based on single observations. Such decision implies a high probability of false alarms. Also, small shifts in the process characteristics, which are of increasing importance from the point of view of efforts for continuous quality improvement, cannot be detected easily ...
M. Xie, T. N. Goh, V. Kuralmani
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EWMA control charts for autoregressive processes
Journal of the Operational Research Society, 2001Summary: Many processes must be monitored by using observations that are correlated. An approach called algorithmic statistical process control can be employed in such situations. This involves fitting an autoregressive-moving average time series model to the data. Forecasts obtained from the model are used for active control, while the forecast errors
Anne B. Koehler +2 more
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