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