Since measures of dispersion are usually called as averages of the second order, they should possess all the qualities of a good average. According to Yule and Kendall, they are as follows
1) It should be easy to calculate and simple to follow.
2) It should be rigidly defined: For the same data, all the methods should produce the same result.
3) It should be based on all the items so as to be more representative.
4) It should be amenable to further algebraic treatment.
5) It should have sampling stability.
6) It should not be unduly affected by the extreme items.