Nonparametric EWMA-Type Control Charts for Monitoring Industrial Processes: An Overview

Abstract

In the present paper we provide an up-to-date overview of nonparametric Exponentially Weighted Moving Average (EWMA) control charts. Due to their nonparametric nature, such memory-type schemes are proved to be very useful for monitoring industrial processes, where the output cannot match to a particular probability distribution. Several fundamental contributions on the topic are mentioned, while recent advances are also presented in some detail. In addition, some practical applications of the nonparametric EWMA-type control charts are highlighted, in order to emphasize their crucial role in the contemporary online statistical process control.

Keywords

• distribution-free statistical methods
• rank-based procedures
• nonparametric statistical process control
• exponentially weighted moving average (ewma) control charts
• sign statistics