Affiliation:
1. Department of Statistics Quaid‐i‐Azam University Islamabad Pakistan
2. School of Mathematical Sciences Universiti Sains Malaysia Penang Malaysia
Abstract
AbstractThe EWMA chart is effective in detecting small shifts in the process mean or process variance. Numerous EWMA charts for the process variance have been suggested in the literature. In this article, new one‐sided and two‐sided EWMA charts are developed for monitoring the variance of a normal process. In developing these new EWMA charts, first, new unbiased estimators of the process variance are developed, followed by incorporating the developed estimators into the new EWMA charts' statistics. The Monte Carlo simulation method is adopted to evaluate the zero‐state and steady‐state run‐length performances of the proposed EWMA variance charts, in comparison with that of three existing EWMA variance charts and the weighted adaptive CUSUM variance chart. The findings reveal that the proposed charts generally perform better than the existing charts. An example of application is given to show the implementation of the proposed and existing charts in detecting increases or decreases in the process variance.
Subject
Management Science and Operations Research,Safety, Risk, Reliability and Quality
Cited by
1 articles.
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