The standard deviation (σ) is a measure of spread in \term{statistics}. It is caclualted by taking the square root of the \term{variance}, which is itself the average of the square of difference of values from their \term{arithmetic mean}. The standard deviation of a simple set of N numbers xi> with mean μ is:
σ = √ ( Σ (xi>− μ)2 / N )
Defined on page 139
Used on pages 138, 139, 140, 162, 207, 209, 258
Links:
alandix.com: standard deviation (s.d., σ)