The synthetic chart combined with an chart (Synthetic- chart) signals when a sample point falls beyond the control limits or when a second point, not far from the first one, falls beyond the warning limits, no matter whether ...

This article proposes two Shewhart charts, denoted np(xy) and np(w) charts, which use attribute inspection to control the mean vector ((x); (y)) of bivariate processes. The units of the sample are classified as first-class, ...

In this article, we propose the S chart with variable charting statistic to control the covariance matrix as an alternative to the use of the bivariate |S| chart and the trivariate VMAX chart. As usual, samples are regularly ...

Traditionally, an (X) over bar chart is used to control the process mean and an R chart is used to control the process variance. However, these charts are not sensitive to small changes in the process parameters. The ...

Control charts are designed to detect assignable causes that may occur in production processes. They are very simple operationally; however, this operational simplicity, that is, taking samples of fixed size n at regular ...

The R chart and the S2 chart are the usual charts for monitoring process dispersion; however, the double sampling (DS) scheme has only be used with the S2 chart. The difficulty in obtaining the properties of the DS R chart ...