Minitab conducts up to four tests for special causes for the Laney P' chart, which detect points beyond the control limits and specific patterns in the data. When a data point fails a test, Minitab reports it in the Session window and marks the point on the chart with a red symbol. A failed point indicates that there is an unusual value or a nonrandom pattern, either of which may be the result of special cause variation. These points should be investigated.

No points failed the tests for special causes.

The data did not fail any of the tests for special causes. Therefore, the chart is in control.