MEASURES OF DISPERSION

The following measures of absolute dispersion are in common use :

 



1) Based on selected items of the data 

i) Range - spread for entire data

ii) Inter Quartile Range - spread for middle 50% data. More commonly Quartile Deviation is used in its place, which is half of inter quartile range.

 

2) Based on all items of the data

i) Mean Deviation - mean of the absolute deviations from central tendency.

ii) Standard Deviation or Root Mean Square Deviation about arithmetic mean

 

3) A Graphic Method - Lorenz Curve (This, however, is not a part of discussion in this course).

 

The relative measures of dispersion corresponding to the measures of absolute dispersion are :

 

 

 Absolute Measures of Dispersion

Relative Measures of Dispersion

i)

Range 

Coefficient of Range

ii)

Quartile Deviation 

Coefficient of Quartile Deviation

iii)

Mean Deviation 

Coefficient of Mean Deviation

iv)

Standard Deviation

Coefficient of Standard Deviation

 

 

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