When using a control chart, the observations outside the upper and lower control limits are ordinarily regarded as nonrandom and worth investigating.

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Yes, observations outside the upper and lower control limits are usually considered as non-random and require investigation because they may indicate the presence of significant special causes of variation that need to be identified and eliminated to improve the process's quality and performance. These observations could also signal data measurement or entry errors or indicate the need to update or review the control limits. It is essential to investigate such occurrences promptly and take appropriate corrective actions to prevent their recurrence and ensure that the process remains stable and predictable.

When Using a Control Chart, the Observations Outside the Upper