What are the Merits and Demerits of Quartile Deviation?
Range is a crude measure because it takes into account only two extreme values i.e. largest and smallest. But quartile deviation gives the difference between upper quartile and lower quartile divided by two.
(i) It is rigidly defined.
(ii) It is superior to range as such its calculation is based on middle 50% of the items of the series.
(iii) It is easy to calculate especially in case of open end series.
(iv) It is not very much affected by the extreme values of the series.
(v) In a moderately systematic series, it enables the computation of lower quartile, upper quartile, standard deviation and mean deviation.
(i) It is not based on all the observations of the series.
(ii) It is not capable of further algebraic treatment.
(iii) It is affected by the fluctuations in sampling.
(iv) It is not understood by a common man.
(v) It is more time consuming.