The extent to which the observations in sample or in a population vary about their mean is called dispersion. A quantity that measures dispersion characteristics is known as a measure of dispersion, scatter or variability. It is desirable to have the measure of dispersion in the same units as the observations. The measure of dispersion is zero when all the observations are equal. It is not affected by change of origin but affected by change of scale.

There are two types of measures of dispersion including, absolute dispersion and relative dispersion. An absolute measure of dispersion is one that measures the dispersion in terms of the same units or in square of units, as the units of data. A relative measure of dispersion is one that is expressed in the form of ratio, co-efficient or percentage and is independent of the units of measurement.

There are two types of measures of dispersion including, absolute dispersion and relative dispersion. An absolute measure of dispersion is one that measures the dispersion in terms of the same units or in square of units, as the units of data. A relative measure of dispersion is one that is expressed in the form of ratio, co-efficient or percentage and is independent of the units of measurement.