Runs

A run of 8 or more consecutively plotted points occurring on one side of the mean is a sign that a shift or trend in the process has begun.

Key:

UCL = Upper Control Limit

LCL = Lower Control Limit

= Mean (average of all the values (subgroup averages))

Note: A plot on the process mean is included in the run.

Runs can indicate a step change in the process, resulting from, for example:

• machine resetting
• management intervention
• a change of parts or method

A run below the mean indicates an improvement on Range, Standard Deviation, and Attribute charts.