Relative Control Chart Study About Monitoring Coeffecient Of Variation Of Process

The Coefficient of Variation(CV) is an important quality characteristic that has several applications in applied statistics, and it has been received an increasing attention in quality control in recent years. Some research achievements about CV have been got.In this paper, two new kinds of control charts are proposed to monitor CV. One is based on the square of sample CV(?γ2), which is integerated with dual EWMA procedure(denoted as DE); the other is based on the standardized version of ?γ2with EWMA procedure(denoted as SE). The performance of these new charts are investigated and the results show that the SE chart performs better than the DE chart. The comparisons between the SE chart and some other existing CV charts is also studied. A real data example is given to illustrate the application of the DE and SE charts.