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An adaptive multivariate EWMA chart
Computers & Industrial Engineering, 2019Abstract The adaptive multivariate EWMA (AMEWMA) and adaptive multivariate CUSUM (AMCUSUM) charts are recently proposed as they provide an overall good detection over a range of mean shift sizes than their non-adaptive conventional counterparts. In this paper, we propose an adaptive MEWMA (AMEWMA) chart for monitoring the infrequent changes in the ...
Abdul Haq, Michael B.C. Khoo
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Quality Technology & Quantitative Management, 2005
AbstractIn this paper, we extend the exponentially weighted moving average (EWMA) technique to double exponentially weighted moving average (DEWMA) technique. We show that DEWMA mean charts perform better than EWMA mean charts in detecting small mean shifts ranging from 0.1 to 0.5 of the process standard deviation, and that the two types of charts ...
Lingyun Zhang, Gemai Chen
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AbstractIn this paper, we extend the exponentially weighted moving average (EWMA) technique to double exponentially weighted moving average (DEWMA) technique. We show that DEWMA mean charts perform better than EWMA mean charts in detecting small mean shifts ranging from 0.1 to 0.5 of the process standard deviation, and that the two types of charts ...
Lingyun Zhang, Gemai Chen
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Journal of Quality Technology, 1998
An exponentially weighted moving average control chart for monitoring Poisson data is introduced. The charting procedure is evaluated using a Markov chain approximation, and its average run length is compared to other procedures for Poisson data. Figure..
Borror, Connie M. +2 more
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An exponentially weighted moving average control chart for monitoring Poisson data is introduced. The charting procedure is evaluated using a Markov chain approximation, and its average run length is compared to other procedures for Poisson data. Figure..
Borror, Connie M. +2 more
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Communications in Statistics - Simulation and Computation, 2004
We propose a new charting procedure, combining two or more Exponentially Weighted Moving Averages (EWMAs), which we call a Composite EWMA (CEWMA) Control Chart. In the case of two EWMAs, the CEWMA chart corresponds to the usual combined Shewhart-EWMA chart, although our plotting procedure remain, we feel, an improvement in application and ...
Lingyun Zhang +3 more
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We propose a new charting procedure, combining two or more Exponentially Weighted Moving Averages (EWMAs), which we call a Composite EWMA (CEWMA) Control Chart. In the case of two EWMAs, the CEWMA chart corresponds to the usual combined Shewhart-EWMA chart, although our plotting procedure remain, we feel, an improvement in application and ...
Lingyun Zhang +3 more
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On t and EWMA t charts for monitoring changes in the process mean
Quality and Reliability Engineering International, 2009AbstractThe performance of an X‐bar chart is usually studied under the assumption that the process standard deviation is well estimated and does not change. This is, of course, not always the case in practice. We find that X‐bar charts are not robust against errors in estimating the process standard deviation or changing standard deviation.
Zhang, Lingyun +2 more
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Monitoring the Coefficient of Variation Using EWMA Charts
Journal of Quality Technology, 2011The coefficient of variation (CV) is a quality characteristic that has several applications in applied statistics and is receiving increasing attention in quality control. This paper suggests a new method to monitor the CV.
CASTAGLIOLA P +2 more
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1992
The control problem of a production process with output Y(t) = M(t) + e(t) (e(t) being a white noise function with E(e(t)) = σ2 for all time points and M(t) := E(Y(t))) can be considered as the problem of monitoring the unknown expectation function M(t).
Joseph J. Hoegel, Hans W. Wolff
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The control problem of a production process with output Y(t) = M(t) + e(t) (e(t) being a white noise function with E(e(t)) = σ2 for all time points and M(t) := E(Y(t))) can be considered as the problem of monitoring the unknown expectation function M(t).
Joseph J. Hoegel, Hans W. Wolff
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CS‐EWMA Chart for Monitoring Process Dispersion
Quality and Reliability Engineering International, 2012Control charts are the most extensively used technique to detect the presence of special cause variations in processes. They can be classified into memory and memoryless control charts. Cumulative sum and exponentially weighted moving average control charts are memory‐type control charts as their control structures are developed in such a way that the ...
Abbas, N., Riaz, M., Does, R.J.M.M.
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Ewma charts for multivariate time series
Sequential Analysis, 1997In this paper a muIt,ivariat.e EWMA chart for time series is introduced. In principle, it is a generalization of the control scheme of Lowry et al. (I992) for multivarite indendent observations. The autocovariances of the EWMA recursion are derived for stationary multivariate time series.
H. G. Kramer, L.V. Schmid
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Effect of autocorrelation on the performance of EWMA chart
International Journal of Productivity and Quality Management, 2012The outputs from the manufacturing processes are often assumed to be independent but actually the observations are correlated and when this correlation builds-up automatically in the entire process, it is called autocorrelation. The performance of a chart is measured in terms of average run length (ARL). The performance of the traditional exponentially-
Sukhraj Singh, D.R. Prajapati
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