Discuss the merits and demerits of mean deviation and standard deviation
Answers
Like any other statistical measure, mean deviation also possesses a number of merits and demerits. These are outlined here as under in the light of the characteristics of an ideal measure of dispersion.
Merits
It is simple to understand.
It is easy to calculate.
It is based on all the observations of a series.
It shown the dispersion, or scatter of the various items of a series from its central value.
It is not very much affected by the values of extreme items of a series.
It facilitates comparison between different items of a series.
It truly represents the average of deviations of the items of a series.
It has practical usefulness in the field of business and commerce.
Demerits
It is not rigidly defined in the sense that it is computed from any central value viz. Mean, Median, Mode etc. and thereby it can produce different results.
It violates the algebraic principle by ignoring the + and – signs while calculating the deviations of the different items from the central value of a series.
It is not capable of further algebraic treatment.
It is affected much by the fluctuations in sampling.
It is difficult to calculate when the actual value of an average comes out in fraction, or recurring figure for that in such a case it requires the use of the shortcut method which involves a cumbersome formula subject to adjustment in different cases.
It is not suitable for sociological study.