Mixed Memory Control Chart For Monitoring The Coefficient Of Variation

In statistical process control,the coefficient of variation(CV)of a population is de-fined as the ratio of the population standard deviation to the population mean,which can be regarded as an important quality characteristic that has widely used in economy and production and other fields.In this paper,a new mixed memory control chart is proposed to monitor CV-mixed EWMA-CUSUM control chart.The new chart is compared with some of the existing two methods by means of average run length(ARL),and the results show that the proposed control chart has better ability to detect the small and moderate shift of the coefficient of variation.Two examples illustrate the use of this chart on real data gathered from a metal sintering process and from a die casting hot chamber process.