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Six Sigma Questions

What does the statement "These defect rates assume a 1.5 sigma shift" mean, found on the bottom of the slide titled "Sigma Levels and Defect Rates"?

The short term sigma level of 6 is equivalent to a long term sigma level of 4.5 (or in essence a 1.5 sigma level "shift"). it is industry standard to refer to 6 six sigma as 3.4 defects per million opportunities assuming this 1.5 sigma shift. It's an allowance for process means to "drift" over the long term.

I'm attaching our DPMO-Sigma Level table for reference. You'll notice that short term sigma level of 6 is equivalent to long term sigma level of 4.5 (a 1.5 sigma difference).

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