Measure of dispersion
It is measure of variability or spread or scatter of data . Dispersion is contrasted with location or central tendency , and together they are the most used properties of distributions .
Types of dispersion
o Range , o Quartile deviation , o Mean deviation , o Standard deviation
Range Range of a series = Maximum value – Minimum value .
48,49,50,50,50,51,52 runs : Range = 52- 48 = 4 ( Shows more consistent performer )
0,25,26,50,50,99,100 runs : Range = 100-0 = 100 Quartile deviation
It is based on the lower quartile and the upper quartile . The difference is called the inter quartile range . The difference divided by is called semiinter-quartile range or the quartile deviation .
Quartile Deviation ( Q . D ) = ( Q3 – Q1 )/ 2
48,49,50,50,50,51,52 runs : Here n = 7 , QD = ( 51-49 )/ 2 = 1