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σ = E[(x - μ)2] = E(x2) - μ2
In statistics, a measure of variability (or spread); the mean-square
deviation from the mean, that is ,
the mean of the squares of the differences between individual values of x
and the mean value μ.
where E denotes expected value. The
positive square root σ of the variance is called the standard
This article is based on NASA's Dictionary of Technical Terms for Aerospace Use