Formula is applied to get median .
Where N is the sum of frequencies , l , f , h and C are , respectively the lower limit , the frequency , the width of the median class and C the cumulative frequency of the class just preceding the median class
Once median is obtained , just apply Mean deviation formula .
Limitations of mean deviation Sample A : 2 , 2 , 2 , 2 , -2, -2, -2, -2 Sample B : 3 , 1 , 3 , 1 , -3, -1, -3, -1
MeanA = MeanB = 0 Mean Deviation about mean for A , B are equal . i . e 2 Variance :
Sample A : 2 , 2 , 2 , 2 , -2, -2, -2, -2 Sample B : 3 , 1 , 3 , 1 , -3, -1, -3, -1 Mean for both Sample A & B is 0 . Aslo number of terms , N in both case is 8 .