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Statistical Process Control. What is a GOOD measure? . Reflects the Voice of the Customer. Ties to business goals. Identifies opportunities to improve the process. Measures are consistent. Types of Variation. Common Cause:. Special Cause:. How to Read a Control Chart.
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What is a GOOD measure? Reflects the Voice of the Customer Ties to business goals Identifies opportunities to improve the process Measures are consistent
Types of Variation • Common Cause: • Special Cause:
Common Vs. Special Causes Region of Special Cause (unexpected) Variation UCL Region of Common Cause (expected) Variation IndividualValue LCL Region of Special Cause (unexpected) Variation TIME
Determining if the Process is “Out of Control” Action Point Statistical Trend 4 of 5 Upper Control Limit Zone A Zone A Zone B Zone B Zone C Zone C Zone C Zone C Zone B Zone B Zone A Zone A Lower Control Limit Process Shift 2 of 3
Special Cause Strategy • Eliminate specific special causes; make an unstable process stable. Get timely data Take immediate action Find out what was different on that occasion. Develop a longer-term remedy that will prevent that recurrence.
Common Cause Strategy • The process shown here is stable. • But does it need to be improved? Customer Needs } Time