Robust Distribution-Free Hybrid Exponentially Weighted Moving Average Schemes Based on Simple Random Sampling and Ranked Set Sampling Techniques

This paper proposes new nonparametric hybrid exponentially weighted moving average (HEWMA) control charts based on simple random sampling (SRS) and ranked set (RSS) techniques using the Wilcoxon rank-sum W statistic. The in-control robustness out-of-control (OOC) performances are thoroughly investigated extensive simulations. HEWMA id="M2"> chart is shown to be superior basic (EWMA) double EWMA id="M3"> in many cases under normal nonnormal distributions. Moreover, OOC sensitivities of id="M4"> -type further improved by supplementary 2-of-2 2-of-3 standard runs-rules approaches. It found that proposed id="M5"> with perform better than id="M6"> SRS RSS charts. Real-life data impurity iron ore used illustrate design implementation