Abstract

A control chart is very useful to control assignable causes that detect the shifted process parameters (e.g., mean and dispersion). Simultaneous monitoring of the process parameters is a well-known approach utilized for the bilateral processes. This paper explores the joint monitoring to study the impact of both process mean and coefficient of variation (CV) by using log-normal transformation under ranked set sampling (RSS) schemes. Utilizing RSS schemes in joint monitoring of mean and CV with exponentially weighted moving average (EWMA) statistic enhances the capacity of the monitoring plan as compare to EWMA with simple random sampling for a mean shift, CV shift as well as joint shift. RSS schemes using EWMA can lessen the antagonistic impact on recognizing the capacity of a joint monitoring plan. The illustration of the proposed control chart is presented with the aid of a real data set.

摘要

控制图对于控制检测偏移过程参数（例如，平均值和离散度）的可分配原因非常有用。工艺参数的同时监测是用于双边工艺的众所周知的方法。本文探讨了联合监测，通过在排序集抽样 (RSS) 方案下使用对数正态变换来研究过程均值和变异系数 (CV) 的影响。与对均值偏移、CV 偏移和联合偏移进行简单随机抽样的 EWMA 相比，在具有指数加权移动平均 (EWMA) 统计数据的均值和 CV 联合监测中使用 RSS 方案增强了监测计划的能力。使用 EWMA 的 RSS 方案可以减少对承认联合监测计划能力的不利影响。