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 = [latex]\sqrt{\dfrac{∑(x_i − μ)^2}{n}}[/latex]

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 = [latex]\sqrt{\dfrac{∑(x_i − \overline {x})^2}{n-1}}[/latex]

In which [latex]\overline {x}[/latex] represents the mean of the results of the sample and n represents the number of results considered.