The EWMA chart for the standard deviation is a useful tool for monitoring the variability of a process quality characteristic. The performance of this chart is usually evaluated under the assumption of known parameters. However, in practice, process parameters are estimated from an in-control...

The and CUSUM control charts are used most widely for monitoring the mean of a quality characteristic x. This article studies the sample sizes and nCUSUM of these two charts in the domain of statistical design. However, the study takes the important sampling inspection cost (including the...

The double sampling (DS) X¯ chart detects small and moderate mean shifts quickly. Furthermore, this chart can reduce the sample size. The DS X¯ chart is usually investigated assuming that the process parameters are known. Nevertheless, the process parameters are usually unknown and are...