Short-term sigma levels correspond to the following long-term DPMO values (one-sided):
1 sigma = 690,000 DPMO = 31% efficiency
2 sigma = 308,000 DPMO = 69.2% efficiency
3 sigma = 66,800 DPMO = 93.32% efficiency
4 sigma = 6,210 DPMO = 99.379% efficiency
5 sigma = 230 DPMO = 99.977% efficiency
6 sigma = 3.4 DPMO = 99.9997% efficiency
These figures assume that the process mean will shift by 1.5 sigma towards the side with the critical specification limit some time after the initial study determining the short-term sigma level. The figure given for 1 sigma, for example, assumes that the long-term process mean will be 0.5 sigma beyond the specification limit, rather than 1 sigma within it, as it was in the short-term study.
Source: en.wikipedia.org/wiki/Six_Sigma
1 sigma = 690,000 DPMO = 31% efficiency
2 sigma = 308,000 DPMO = 69.2% efficiency
3 sigma = 66,800 DPMO = 93.32% efficiency
4 sigma = 6,210 DPMO = 99.379% efficiency
5 sigma = 230 DPMO = 99.977% efficiency
6 sigma = 3.4 DPMO = 99.9997% efficiency
These figures assume that the process mean will shift by 1.5 sigma towards the side with the critical specification limit some time after the initial study determining the short-term sigma level. The figure given for 1 sigma, for example, assumes that the long-term process mean will be 0.5 sigma beyond the specification limit, rather than 1 sigma within it, as it was in the short-term study.
Source: en.wikipedia.org/wiki/Six_Sigma
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