What Control Charts Look Like

All control charts have four major sections:

• Information section
• Data section
• Graph section
• Comments section

An area of the control chart that is often overlooked is the Comments section.

• If your process has gone out-of-control, the notes in this section will give you clues as to why the process went out-of-control.

All control chart graphs have a centerline and upper and lower control limits.

• The centerline represents the process mean, or grand average, for the process.
• The upper and lower control limits show the extents of the common cause variation in the process. They approximate plus and minus three standard deviations from the process mean.