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"].
(2003-05-06)
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