New EWMA S2 Control Charts for Monitoring Process Dispersion
New EWMA S2 Control Charts for Monitoring Process Dispersion
The exponentially weighted moving average (EWMA) control chart is an effective tool for the detection of small shifts in the process variability. This research studied the properties of EWMA charts based on unbiased sample variance for monitoring of changes in the process dispersion. However, since an increase in process variance …