standard deviation

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standard deviation

[′stan·dərd ‚dē·vē′ā·shən]
(statistics)
The positive square root of the expected value of the square of the difference between a random variable and its mean.

standard deviation

see MEASURES OF DISPERSION.

standard deviation

(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].

["Barrons Dictionary of Mathematical Terms, second edition"].

standard deviation

In statistics, the average amount a number varies from the average number in a series of numbers.
References in periodicals archive ?
Z], converges to the parameter that it estimates, the population standard deviation, [[sigma].
However, with knowledge of the population standard deviations of the parameters that make up the SIG, a 95% confidence interval (CI) for SIG can be indirectly derived using methods of static (Monte Carlo) simulation.
1] are the sample standard deviations computed from historical data and are the estimates of the population standard deviations [[sigma].

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