Lecture on Measures of Variations

Variability refers to the extent to which the observations vary from one another from some average. A measure of  variation is designed to state the extent to which the individual  measures  differ on an average from the mean.

Measures of variations are needed for four basic purposes:

  • To determine the reliability of an average;
  • To serve as a basis for the control of the variability;
  • To compare two or more series with regard to their variability;
  • To facilitate the use of other statistical measures