Square root of the variance of a statistical variable.
Symbols
In the case of an entire population the standard deviation is noted as “σ”.
In the case of a sample population, the standard deviation is generally noted as “s”.
Formula
In the case of an entire population, the standard deviation is found by applying this formula:
σ = \(\sqrt{\dfrac{∑(x_i − μ)^2}{n}}\)
In which μ represents the arithmetic mean of the distribution and n represents the number of results in the population.
In the case of a sample of this distribution, the standard deviation is found by applying this formula:
s = \(\sqrt{\dfrac{∑(x_i − \overline {x})^2}{n-1}}\)
In which \(\overline {x}\) represents the mean of the results of the sample and n represents the number of results considered.