Common Cause Variation DCOVA Total Process Common Cause Special Cause Variation Variation Variation Common cause variation naturally occurring and expected the result of normal variation in materials,tools,machines,operators, and the environment Statistics for Managers Using Microsoft Excel Statistics for Managers Using Microsoft Excel Common Cause Variation Total Process Variation Common Cause Variation Special Cause Variation = + Common cause variation  naturally occurring and expected  the result of normal variation in materials, tools, machines, operators, and the environment DCOVA