Efficient Auxiliary Information–Based Control Charting Schemes for the Process Dispersion with Application of Glass Manufacturing Industry

Abstract

The hybrid exponentially weighted moving average (HEWMA) control chart is an enhanced version of the EWMA control chart that monitors the process parameters effectively. Similarly, the auxiliary information-based (AIB) EWMA control charts are very efficient for monitoring process parameters. The purpose of this paper is to propose two new control charts for the improved monitoring of process dispersion referred to as ${\text{HEWMA}}_{\text{AIB}}^{\left(1\right)}$ and ${\text{HEWMA}}_{\text{AIB}}^{\left(2\right)}$ control charts. A simulation study is carried out to assess the performance of the proposed ${\text{HEWMA}}_{\text{AIB}}^{\left(1\right)}$ and ${\text{HEWMA}}_{\text{AIB}}^{\left(2\right)}$ control charts. Average run length, extra quadratic loss, relative average run length, and performance comparison index are used to compare the performance of the proposed control charts against the existing counterparts. The comparisons reveal the superiority of the proposed control charts against other competing control charts, particularly for small to moderate shifts in the process dispersion. Finally, a real-life data set from the glass industry is used to demonstrate the practical implementation of the proposed control charts.