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