# standard deviation

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.
Origin of standard deviation
1920-1925
1920-25
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for standard deviation
Historical Examples
• For each measurement, the coefficient of variation, standard deviation and probable error were computed.

E. Raymond Hall
• This is called the index of variability or "standard deviation."

William E. Kellicott
• And against the first target the accuracy observed was about .7 mils, in standard deviation.

The President's Commission on the Assassination of President Kennedy
British Dictionary definitions for standard deviation

## standard deviation

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
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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standard deviation in Medicine

standard deviation n.
Symbol σ
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.

The American Heritage® Stedman's Medical Dictionary
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standard deviation in Science
 standard deviation   (stān'dərd)    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.
The American Heritage® Science Dictionary
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standard deviation in Culture

### standard deviation definition

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.

Note: About sixty-eight percent of the data are within one standard deviation of the mean.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
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standard deviation in Technology
statistics
(SD) A measure of the range of values in a set of numbers. Standard deviation is 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.
The standard deviation of a random variable or list of numbers (the lowercase greek sigma) is the square of the variance. The standard deviation of the list x1, x2, x3...xn is given by the formula:
sigma = sqrt(((x1-(avg(x)))^2 + (x1-(avg(x)))^2 + ... + (xn(avg(x)))^2)/n)
The formula is used when all of the values in the population are known. If the values x1...xn are a random sample chosen from the population, then the sample Standard Deviation is calculated with same formula, except that (n-1) is used as the denominator.
[dictionary.com (http://dictionary.com/)].
["Barrons Dictionary of Mathematical Terms, second edition"].
(2003-05-06)
The Free On-line Dictionary of Computing, © Denis Howe 2010 http://foldoc.org
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### Difficulty index for standard deviation

Few English speakers likely know this word

### Word Value for standard

10
11
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