Economic design of x̄&s control chart based on deployed manpower and random process shift

This article presents an x&&S control chart (known as x̄&S-M chart) for monitoring shifts in mean and standard deviation of a process. The design algorithm searches for the appropriate amount of manpower that should be deployed to minimize the total cost associated with the implementation of the SPC (Statistical Process Control) scheme considering random process shift. The design parameters such as the sample size, sampling interval and control limits of the control chart are also optimized in the mean time. An example shows that the proposed design algorithm cuts down the total cost associated with the SPC scheme to a significant degree. Even though, the discussion is limited to the design of x̄&S chart, the general idea can be applied to many other charts such as the CUSUM and EWMA charts. © 2008 ICQR.