0,25,26,50,50,99,100 runs : Here n = 7 , QD = ( 99-25 )/ 2 = 37
The quartile deviation is a slightly better measure of absolute dispersion than the range . But it ignores the observation on the tails .
Mean deviation about point a : It determines the Mean deviation about a given point .
Commonly used Mean deviation about any point are : Mean deviation about Mean
Mean deviation about Median
Numerical : Let ’ s find mean deviation about the median for the following data : 48,49,50,50,50,51,52 runs & 0,25,26,50,50,99,100 runs .
Solution : Median is 50 for both case . Case 1 : 48,49,50,50,50,51,52 runs . Deviation from Mean ( 50 ) is | Data-Mean | Mean Deviation = ( 2 + 1 + 0 + 0 + 0 + 1 + 2 )/ 7 = 6 / 7 runs
Case 2 : 0,25,26,50,50,99,100 runs Deviation from Mean ( 50 ) is | Data-Mean |
Mean Deviation = ( 50 + 25 + 24 + 0 + 0 + 49 + 50 )/ 7 = 198 / 7 runs