# standard deviation

Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Acronyms, Wikipedia.
Related to standard deviation: variance

## 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 ?
So, having an instructor who is 1 standard deviation more effective produces a test score change that is larger than the gap between 25- and 35-year-old students, and comparable to the gap between students entering the class with a 3.
Therefore, it is enough to collect a set of frequency measurements, that are started randomly, to estimate the expected values of error and standard deviation of the frequency measurements.
A quick approximation for the standard deviation can be made using the range rule.
Real GDP growth at historical average minus one standard deviation in 2014-15###30###29###28###26###25###24###20###13
Standard deviation is the measure of how actual events differed from what was expected.
She added that some of the kids who participated in the study were two or even three standard deviations away from the average, and their kindergarten indicators were correspondingly worse than those who were one standard deviation away.
In Table III we can see that the mean results in STAI (anxiety) test for control subjects are 42,13, with a standard deviation of 6,10, and the mean for intervention group is 57,80, with a standard deviation of 8,79, being this difference statistically significant (df = -11,871; [rho] = ,012).
The mean birth weight standard deviation was significantly greater in the IL-10 positive group (0.
Standard deviation of this distance by applying mathematical statistic laws is computed from the formula
Second, we identify whether all business cycles have the same mean and standard deviation by calculating them for each business cycle as well as for the complete sample period.
Those participants that initially had a low standard deviation also showed some improvement in repeatability, with their standard deviations decreasing by 11-16%.

Site: Follow: Share:
Open / Close