standard deviation


Definition of standard deviation

1 : a measure of the dispersion of a frequency distribution that is the square root of the arithmetic mean of the squares of the deviation of each of the class frequencies from the arithmetic mean of the frequency distribution also : a similar quantity found by dividing by one less than the number of squares in the sum of squares instead of taking the arithmetic mean
2 : a parameter that indicates the way in which a probability function or a probability density function is centered around its mean and that is equal to the square root of the moment in which the deviation from the mean is squared

Examples of standard deviation in a Sentence

Recent Examples on the Web They are standardized so that the typical range is 0 to 100, the mean is 50 and the standard deviation is 10. WSJ, "Methodology for the Management Top 250 Company Rankings," 12 Dec. 2020 This is expressed in terms of the extreme spread (ES) of measured velocities of a shot string that’s been chronographed, and the standard deviation (SD) of that data. John B. Snow, Outdoor Life, "The 6 GT Is a New Top Cartridge in the Precision Rifle World," 5 Oct. 2020 Haklay and Gopher used a computer algorithm based on standard deviation mapping to analyze the site’s underlying architecture. Alex Fox, Smithsonian Magazine, "Did Geometry Guide the Construction of the World’s Oldest Temple?," 28 May 2020 One reason for the relatively modest performance reflected in the Eurekahedge data may be that under a common definition -- an event more than three standard deviations from the norm -- last week’s market moves didn’t necessarily qualify as a tail. Yakob Peterseil,, "Black Swan Fund That Won Big in 2008 Has Best Month Since Crisis," 5 May 2020 Between 2013 and the time the suit was filed in 2017, the DOL found, the salaries women received as compared to their male peers were between 2.71 and 8.41 standard deviations lower, depending on job category. Kate Cox, Ars Technica, "DOL’s $400M pay-discrimination suit is unconstitutional, Oracle argues," 5 Dec. 2019 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, "Is the Universe a Giant Loop?," 5 Nov. 2019 The salary paid to black employees, adjusted for the same variables, had a standard deviation 2.10 lower than the compensation for white men, and for Asian employees the difference was -6.55. Kate Cox, Ars Technica, "DOL’s $400M pay-discrimination suit is unconstitutional, Oracle argues," 5 Dec. 2019 But standard deviations are paramount when considering early season trips, when the winter is young and ski resorts with higher propensities for drought and rain stand higher odds of having small amounts of terrain open. New York Times, "The Snowiest Mountains: Where to Ski, and When," 27 Nov. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'standard deviation.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of standard deviation

1894, in the meaning defined at sense 1

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The first known use of standard deviation was in 1894

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Last Updated

21 Jan 2021

Cite this Entry

“Standard deviation.” Dictionary, Merriam-Webster, Accessed 5 Mar. 2021.

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