Usefulness of Measures of Dispersion:
1) It is helpful for determining the reliability of an average. It points out the extent to which the average is the representative of the entire data.
2) It enables comparison of two or more distributions with regard to their variability.
3) It is instrumental to determine the nature and cause of variation in order to control the variation itself.
4) It facilitates the calculation of other statistical measures like correlation, regression etc.