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.
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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.