Which type of variation is caused by factors outside a system?

Special cause variation refers to variations that arise from specific, identifiable factors outside of the regular system or process. These causes can result from unusual events or disruptions and are not considered part of the inherent variability of the system. Identifying special cause variations is crucial because they indicate that something unusual has happened, which can prompt further investigation and corrective action to address the specific issue.

This type of variation often highlights opportunities for improvement or issues that need to be resolved, distinguishing it from common-cause variation, which represents the natural, normal fluctuations within the system due to inherent processes. Understanding the difference between these two types of variations is essential for effective quality management and process control.