Merits of Standard Deviation:
Among all measures of dispersion Standard Deviation is considered superior because it possesses almost all the requisite characteristics of a good measure of dispersion. It has the following merits:
1) It is rigidly defined.
2) It is based on all the observations of the series and hence it is representative.
3) It is amenable to further algebraic treatment.
4) It is least affected by fluctuations of sampling.
1) It is more affected by extreme items.
2) It cannot be exactly calculated for a distribution with open-ended classes.
3) It is relatively difficult to calculate and understand.