sigma
noun
sig·ma ˈsig-mə 
1
: the 18th letter of the Greek alphabet see Alphabet Table
2
: standard deviation
Example Sentences
Recent Examples on the Web According to the group’s calculations, the Planck data point to a closed universe with a standard deviation of 3.5 sigma (a statistical measurement that means about 99.8% confidence that the result isn’t due to random chance). 
Rafi Letzter, Scientific American, 5 Nov. 2019 Thomson and his team must reach five-sigma certainty to definitively claim a discovery. Quanta Magazine, 14 May 2015 Historically, most industrial companies operate between three and four sigma, making them between 93% and 99.3% defect-free (these figures can vary slightly depending on the statistical model). Oliver Staley, Quartz at Work, 3 Sep. 2019 The gold standard for discovery is a five-sigma result, comparable to tossing 21 heads in a row. Jennifer Ouellette, Quanta Magazine, 18 July 2013 Through regular reports released under the name sigma, the company offers a lens into the changing trends of the insurance world. David Grossman, Popular Mechanics, 17 Apr. 2019 Typically, only five sigma is needed to call something a discovery. John Timmer, Ars Technica, 28 June 2018 Physicists and astronomers, however, aren't usually convinced that two phenomena are connected until there's no more than a one in 3.5 million, or 5 sigma, probability of a coincidence. Daniel Clery, Science | AAAS, 12 July 2018 Physics requires a statistical significance of five sigma to declare discovery; MiniBooNE is tantalizingly close and will probably be there within the next two years. John Timmer, Ars Technica, 8 June 2018 See More
Rafi Letzter, Scientific American, 5 Nov. 2019 Thomson and his team must reach five-sigma certainty to definitively claim a discovery. Quanta Magazine, 14 May 2015 Historically, most industrial companies operate between three and four sigma, making them between 93% and 99.3% defect-free (these figures can vary slightly depending on the statistical model). Oliver Staley, Quartz at Work, 3 Sep. 2019 The gold standard for discovery is a five-sigma result, comparable to tossing 21 heads in a row. Jennifer Ouellette, Quanta Magazine, 18 July 2013 Through regular reports released under the name sigma, the company offers a lens into the changing trends of the insurance world. David Grossman, Popular Mechanics, 17 Apr. 2019 Typically, only five sigma is needed to call something a discovery. John Timmer, Ars Technica, 28 June 2018 Physicists and astronomers, however, aren't usually convinced that two phenomena are connected until there's no more than a one in 3.5 million, or 5 sigma, probability of a coincidence. Daniel Clery, Science | AAAS, 12 July 2018 Physics requires a statistical significance of five sigma to declare discovery; MiniBooNE is tantalizingly close and will probably be there within the next two years. John Timmer, Ars Technica, 8 June 2018 See More Word History
Etymology
Greek
First Known Use
1584, in the meaning defined at sense 1