standard deviation

American  

noun

Statistics.

1. a measure of dispersion in a frequency distribution, equal to the square root of the mean of the squares of the deviations from the arithmetic mean of the distribution.

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standard deviation British  

noun

1. statistics a measure of dispersion obtained by extracting the square root of the mean of the squared deviations of the observed values from their mean in a frequency distribution

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standard deviation Scientific  

/ stăn′dərd /

1. A statistic used as a measure of the dispersion or variation in a distribution, equal to the square root of the arithmetic mean of the squares of the deviations from the arithmetic mean.

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standard deviation Cultural  

1. In statistics, a measure of how much the data in a certain collection are scattered around the mean. A low standard deviation means that the data are tightly clustered; a high standard deviation means that they are widely scattered.

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Discover More

About sixty-eight percent of the data are within one standard deviation of the mean.

Etymology

Origin of standard deviation

First recorded in 1920–25

Compare meaning

How does standard-deviation compare to similar and commonly confused words? Explore the most common comparisons:

• standard deviation vs. standard error

Example Sentences

And yet the VIX finished Friday above 27, a level that is roughly one standard deviation above the index’s long-term average.

From MarketWatch • Mar. 14, 2026

At estimated 2027 price-to-book of 0.95X, banking stock valuations appear undemanding, trading one standard deviation below its five-year mean price-to-book of 1.07X, he says.

From The Wall Street Journal • Mar. 3, 2026

Each standard deviation drop in relative amplitude was linked to a 54% increase in dementia risk.

From Science Daily • Jan. 3, 2026

New York provides a range of standard deviation, specifying a 68% probability that the GDP figure will fall between 1.07% and 3.99%.

From Los Angeles Times • Oct. 10, 2023

No other breed falls outside the standard deviation.

From "The Miscalculations of Lightning Girl" by Stacy McAnulty