Statistics Toolbox

Control Charts

These graphs were popularized by Walter Shewhart in his work in the 1920s at Western Electric. A control chart is a plot of a measurements over time with statistical limits applied. Actually, control chart is a slight misnomer. The chart itself is actually a monitoring tool. The control activity may occur if the chart indicates that the process is changing in an undesirable systematic direction.

The Statistics Toolbox supports three common control charts, described in the following sections:

• Xbar Charts
• S Charts
• EWMA Charts

Statistical Process Control

Xbar Charts