Process Variation DCOVA Total Process Common Cause Special Cause Variation Variation Variation Variation is natural;inherent in the world around us No two products or service experiences are exactly the same With a fine enough gauge,all things can be seen to differ Statistics for Managers Using Microsoft Excel
Statistics for Managers Using Microsoft Excel Process Variation Total Process Variation Common Cause Variation Special Cause Variation = + Variation is natural; inherent in the world around us No two products or service experiences are exactly the same With a fine enough gauge, all things can be seen to differ DCOVA
Total Process Variation DCOVA Total Process Common Cause Special Cause X Variation Variation Variation Variation is often due to differences in: ■People ■Machines ■Materials ■Methods ■ Measurement Environment Statistics for Managers Using Microsoft Excel
Statistics for Managers Using Microsoft Excel Total Process Variation Total Process Variation Common Cause Variation Special Cause Variation = + People Machines Materials Methods Measurement Environment Variation is often due to differences in: DCOVA
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
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 Excel
Statistics 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
Two Kinds Of Errors DCOVA Treating common cause variation as special cause variation Results in over overadjusting known as tampering Increases process variation Treating special cause variation as common cause variation Results in not taking corrective action when it should be taken Utilizing control charts greatly reduces the chance of committing either of these errors Statistics for Managers Using Microsoft Excel
Statistics for Managers Using Microsoft Excel Two Kinds Of Errors Treating common cause variation as special cause variation Results in over overadjusting known as tampering Increases process variation Treating special cause variation as common cause variation Results in not taking corrective action when it should be taken Utilizing control charts greatly reduces the chance of committing either of these errors DCOVA