Sigma

sigma (σ or s) : Lowercase Greek letter that stands for standard deviation. The symbol "σ " refers to the standard deviation of an entire population of items. The symbol "s" refers to the standard deviation of a sample of items.

[Category=Data Quality ]

Source: Larry English, http://www.iaidq.com/main/glossary.shtml , 10-Feb-2009 12:43

Sigma (Σ) : Uppercase Greek letter that stands for the summation of a group of numbers.

[Category=Data Quality ]

Source: Larry English, http://www.iaidq.com/main/glossary.shtml , 10-Feb-2009 12:43

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Sigma - One standard deviation in a normally distributed process.

[Category=Quality ]

Source: American Society for Quality, 21 October 2010 09:06:10, http://www.asq.org/glossary/

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Sigma - The Greek letter s (sigma) refers to the standard deviation of a population. Sigma, or standard deviation, is used as a scaling factor to convert upper and lower specification limits to Z. Therefore, a process with three standard deviations between its mean and a spec limit would have a Z value of 3 and commonly would be referred to as a 3 sigma process.

[Category=Data Quality ]

Source: iSixSigma, 23 February 2011 09:04:39, https:web.archive.org/web/20111109014246/http:www.isixsigma.com/index.php?option=com_glossary