Statistical process control has been widely applied to manufacturing and service operations with the aim of monitoring and improving the reliability of products. The existing monitoring procedures were introduced following the assumption that a single-stage process with independent quality...

An x-bar chart is a statistical device used for the study and control of a process. Control charts based on the three sigma limits were produced and have been used effectively for a long time. In today¡¯s developed and developing countries, companies have introduced Six Sigma initiatives in...