New Shewhart-EWMA and Shewhart-CUSUM control charts for monitoring process mean

Abstract

This study proposes new Shewhart-EWMA (SEWMA) and Shewhart-CUSUM (SCUSUM) control charts using Varied L Ranked Set Sampling (VLRSS) for monitoring the process mean, namely the SEWMA-VLRSS and SCUSUM-VLRSS charts. The run length characteristics of the proposed charts are computed using extensive Monte Carlo simulations. The proposed charts are compared with their existing counterparts in terms of the average and standard deviations of run lengths. It is found that, with perfect and imperfect rankings, the SEWMA-VLRSS and SCUSUM-VLRSS charts are more sensitive than their analogous charts based on simple random sampling, Ranked Set Sampling (RSS), and median RSS schemes. A real dataset is also used to explain the implementation of the proposed control charts.