Measures of Dispersion — Economics STD 11 Commerce — Question

Techniques that are used to measure the extent of variation or the deviation (also called degree of variation) of each value in the data set from a measure of central tendency, usually the mean or median. Such statistical techniques are called measures of dispersion (or variation).
An average is a single value that represents a set of values in a distribution. It is the central value which represents the entire distribution.
Dispersion on the other hand, measures the extent to which the individual value fall away from the central value.