In Six Sigma, "sigma" is actually a statistical measure of standard deviation. It represents how far a process is from perfect. Six Sigma seeks to have minimal defects and variations while achieving near-perfect quality with a mere 3.4 defects per million opportunities.
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its a statistical term for standard diviation.
in normal distribution if there are six standard deviations between the process mean and the nearest specification limit, then there is a 99.99966% probability that no items will fail to meet specifications .
In six sigma 1.5 sigma correction is considered to allow the natural variation present in any process. So when we say that process is sis sigma , it is nactually 4.5 sigma.
If Six Sigma = 0.999999, then in percentage terms that would be 99.9999%.
3 Sigma is 66800 defects per million pieces 6 Sigma is 3-4 defects per million pieces You can check out the number of defective pieces per million & the % accuracy for all Sigma levels in the six sigma conversion chart in the related links section
Quantitative skills
its not a word its a greek letter
sigma represents standard deviation. In a normal distribution, +/- 1 sigma from the mean, for instance, corresponds to approximately 67% of the area under the normal distribution. +/- 2 sigma corrresponds to 95% of the area and +/- 3 sigma from the mean corresponds to 99% of the area under a normal distribution. The area that is covered under +/- six sigma from the mean corresponds to nearly 100% -- that is, the part of the area NOT under that +/- 6 sigma is in the 10^-15 range or 1/1,000,000,000,000,000. The six sigma name borrows from this to suggest that the method gives this degree of certainty: that in 999,999,999,999,999 in 1,000,000,000,000,000 cases the result will be predictable. It does nothing, however, to explain how an agricultural process management methodology applies to other fields.