Which two types of variations make up process variation?

In the context of process variation, the two types are common cause and special cause variation. Common cause variation, also known as natural variation, refers to the inherent fluctuations in a process that occur as a result of the system's design and consistent operating conditions. These variations are generally predictable and tend to be consistent over time.

On the other hand, special cause variation, sometimes referred to as assignable cause variation, arises from specific, identifiable factors that are not part of the process's inherent operation. These variations are typically unexpected and can yield significant changes in performance or outcome when they occur. Recognizing and addressing special cause variation is crucial for improving processes since it indicates that something unusual has influenced the results, whereas common cause variation indicates that improvements may need to be made to the overall system.

Understanding the distinction between these two types of variations is fundamental in Total Quality Management (TQM) and is essential for effective problem-solving and continual improvement in processes. By identifying and managing these variations appropriately, organizations can enhance their process stability and overall quality.