What characterizes a special cause variation?

A special cause variation is characterized by occurring due to unexpected or unusual events. This type of variation is not consistent or predictable, making it distinct from common cause variation, which is inherent to the process and expected as part of the normal operational environment.

When a special cause variation is observed, it suggests that there is an anomaly or exceptional circumstance affecting the process. These events may arise from various sources such as machine breakdowns, external factors like supply chain disruptions, or changes in workforce behavior. Identifying and addressing these special causes is crucial for maintaining quality and stability in processes, as they can lead to significant deviations from the desired performance levels.

In contrast, common cause variations are a natural part of a process and can typically be anticipated and managed through process design and control measures. Recognizing the difference between special cause and common cause variations is essential for effective quality management, as it influences how problems are addressed and corrective actions are formulated.