Final answer:
Assignable cause variation refers to variations in a process that can be attributed to specific, identifiable causes, while common cause variation represents the natural variation that occurs in any process. Examples of assignable cause variation include a malfunctioning machine, a change in raw materials, or operator errors.
Step-by-step explanation:
Assignable cause variation refers to variations in a process that can be attributed to specific, identifiable causes. These causes are usually external to the process and can be controlled or eliminated. Examples of assignable cause variation include a malfunctioning machine in a production line, a change in the raw materials used, or an error made by an operator.
On the other hand, common cause variation, also known as random variation, is inherent to a process and cannot be easily attributed to a specific cause. It represents the natural variation that occurs in any process, even when everything is functioning as intended.
Examples of common cause variation include minor fluctuations in temperature, slight variations in input materials, or the inherent variability in human performance.
Distinguishing between assignable cause variation and common cause variation is important for process improvement. Assignable cause variation can be identified and eliminated, leading to improved process performance and reduced variation.
Common cause variation, on the other hand, represents the inherent limitations of a process and can only be reduced by making fundamental changes to the process itself.