The upper control limit is calculated from the data that is plotted on the control chart. It is placed 3 sigma (of the data being plotted) away from the average line.

The following statements create the chart shown in Output 38.4.1 ... and it is decided to eliminate these batches from the data set and recompute the control limits. The following statements create a ...

On a Shewhart chart, upper and lower control limits are used to decide whether a point signals an out-of-control condition. On a cusum chart, the limits take the form of a decision interval or a ...