期刊名称：International Journal of Innovative Research in Science, Engineering and Technology
印刷版ISSN：2347-6710
电子版ISSN：2319-8753
出版年度：2014
期号：ICIET
页码：1055
出版社：S&S Publications
摘要：Control charts have been used to monitorand control the production process and generate some sortof signal when there are indications to the effect that theprocess has gone out of control. Conventional (Shewhart)X charts were originally developed by Walter F.Shewhart (1931). The limits of the chart are known asupper control limit (UCL) and lower control limit (LCL).He suggested two control limits i.e. UCL = X + 3σ/√nand LCL = X - 3σ/√n, where X is the target mean, σ ispopulation standard deviation and n is the sample size. Inimplementing the X chart, it is assumed that the processoutputs must be IID but usually there is some correlationamong the data. When this correlation builds upautomatically in the entire process, this phenomenon iscalled autocorrelation. It is found that the performance ofconventional X chart deteriorates on increasing the levelof correlation.
关键词：Average run length; sample size; X;charts; IID data and Autocorrelation
