What type of variation is considered to be due to specific, identifiable forces?

Special Cause Variation refers to variation in a process that can be attributed to specific, identifiable sources or factors that are not inherent to the process itself. This type of variation typically arises from unusual circumstances, changes in the process, or external influences. Identifying and understanding these causes is crucial for quality improvement, as they present opportunities for intervention and control.

For instance, if a manufacturing line experiences a sudden spike in defects due to a malfunctioning machine, this is a clear example of Special Cause Variation. By addressing the specific issue with the machine, the process can return to its normal state.

In contrast, Common Cause Variation, Systematic Variation, and Natural Variation generally refer to variations that are inherent in the process itself or result from routine operating conditions. These forms of variation are typically more stable and predictable, often requiring different strategies for management and control. Therefore, the focus on Special Cause Variation highlights the importance of identifying and acting upon specific anomalies to maintain quality standards in processes.