Monitoring Industrial Process using a Robust Modified Mean Chart

Shewhart control chart is the most popular and widely used Statistical process Control
tool to monitor process. It is developed under the assumption of independent and normally
distributed process. In order to control process mean and standard deviation, robust
estimator of these parameters can be better alternatives as charts based on that are more
resistant to moderate changes in process distribution. Modied Maximum Likelihood
Estimator (MMLE) for mean and standard deviation is a pair of statistics with good
robust properties. Authors introduced these measures to control charting process and
investigate the advantages of using it. A modication to mean based on MMLE and
its standard deviation are introduced to improve industrial process performance. Using
Monte Carlo simulation method, performance of this chart is compared with classical
control chart. Performance is also studied based on the Average Run Length.