Special Cause Variation DCOVA Total Process Common Cause Special Cause Variation Variation Variation Special cause variation abnormal or unexpected variation has an assignable cause variation beyond what is considered inherent to the process Statistics for Managers Using Microsoft ExcelStatistics for Managers Using Microsoft Excel Special Cause Variation Total Process Variation Common Cause Variation Special Cause Variation = + Special cause variation  abnormal or unexpected variation  has an assignable cause  variation beyond what is considered inherent to the process DCOVA