Abstract
The cumulative sum control chart is known as a control chart sensitive to a slight change in lot quality characteristics. Further, in this control chart, the user can determine chart parameters according to the degree of change in quality characteristics which the user wants to detect. On the other hand, Kanagawa et al.have proposed the(x^^-, s)simultaneous control chart which enables the user to monitor both changes of the mean and the variance simultaneously for normally distributed characteristics. In this paper, we consider a cumulative sum(x^^-, s)simultaneous control chart in order to improve the control feature for a slight change in quality characteristics. In addition, the economical operation of the cumulative sum(x^^-, s)simultaneous control chart is also considered.
