New modified exponentially weighted moving average-moving average control chart for process monitoring

Multivariate Exponentially Weighted Moving Average Chart for Monitoring Poisson Observations∗

In many practical situations, multiple variables often need to be monitored simultaneously to ensure the process is in control. In this article, we develop a feasible multivariate monitoring procedure based on the general Multivariate Exponentially Weighted Moving Average (MEWMA) to monitor the multivariate count data. The multivariate count data is modeled using Poisson-Lognormal distribution ...

A new exponentially weighted moving average control chart for monitoring the coefficient of variation

Monitoring coefficient of variation is one of the successful approaches to Statistical Process Control (SPC) when the process mean and standard deviation are not constants. This paper presents a modified Exponentially Weighted Moving Average (EWMA) chart in order to further enhance the sensitivity of the EWMA control chart proposed by Castagliola et al. (2011). Tables are provided for the stati...

Design of Exponentially Weighted Moving Average Chart for Monitoring Standardized Process Variance

Control charts for monitoring of process variance are developed based on Shewhart, exponentially weighted moving average (EWMA) and cumulative sum (CUSUM) control charts for mean. In all these variance control charts, log transformation of the sample variance is used. The design procedure of this chart is complex and it is poorly understood by the industry. In this paper a EWMA chart for monito...

Average Run Length Performance for Multivariate Exponentially Weighted Moving Average Control Chart Procedure with Application

The drawbacks to multivariate charting schemes is their inability to identify which variable was the source of the signal. The multivariate exponentially weighted moving average (MEWMA) developed by Lowry, et al (1992) is an example of a multivariate charting scheme whose monitoring statistic is unable to determine which variable caused the signal. In this paper, the run length performance of m...

A Robust Exponentially Weighted Moving Average Control Chart for the Process Mean