Location charts based on ranked set sampling for normal and non-normal processes

Abstract

Control charts, based on ranked set sampling schemes, had been proposed recently for efficient monitoring of process location. All the proposals in the literature are based on the ideal assumption of normally distributed quality characteristics. No study as of yet investigated the performance of location charts based on ranked set sampling for non-normal processes. In this study, we investigated the location (Formula presented.) chart based on simple random sampling (SRS) and three well-known rank-based schemes ie, ranked set sampling (RSS), median ranked set sampling (MRSS), and extreme ranked set sampling (ERSS), considering normal and a variety of non-normal parent distributions. Both heavy-tailed symmetric and skewed cases have been considered in this study. The performance of the charts is evaluated using average run length (ARL), extra quadratic loss (EQL), and relative ARL (RARL) measures. A real life example is also presented that details the monitoring of pH levels in water for an experiment conducted to study the reproduction of Mysids. The study will help quality practitioners to choose the (Formula presented.) chart based on an efficient sampling scheme for normal and non-normal processes. - 2019 John Wiley & Sons, Ltd.