Variance, Standard Deviation and Relative Variability


Variance can be explained as the process of measuring how the items would disperse about their mean. For the variance (σ2) of overall population can be given by the equation:

Variance of Population

Variance (s2) would be calculated in a different way:

Variance of Sample

Standard Deviation

The square root of variance is known as standard deviation. (Hence, for population we can say the standard deviation is nothing but the square root of square deviation's average from mean.)

Both Standard deviation and variance are very closely related as both are useful for finding the variability. i.e, square root of variance is known as standard deviation and the average of the square difference is known as the variance.

Relative Variability

The standard deviation divided by its mean of a set is known as relative variability. Relative variability comes handy while we compare numerous variances.

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