Coefficient of variation

The coefficient of variation is a normalised measure of dispersion of a probability distribution. It is defined as the ratio of the standard deviation to the mean:

This is only defined for non-zero mean, and is most useful for variables that are always positive. It is often reported as a percentage (%) by multiplying the above calculation by 100.

The absolute value of the coefficient of variation expressed as a percentage is often referred to as the relative standard deviation (RSD or %RSD).