A healthcare quality professional is looking at a control chart and notices that last November...

A point exceeding the upper control limit on a control chart indicates special cause variation, meaning the variation is due to an assignable or unusual factor, not just random or common cause variation (Institute for Healthcare Improvement, Statistical Process Control, 2023; The Joint Commission, Performance Improvement Standards, 2024).

Random or normal variation occurs within control limits.

Common cause variation is inherent and stable within the system.