Explanation:
It is the average (mean) of the absolute values of the differences between a set of numbers and their mean.
Example: consider the set {1, 2, 4}. The mean is computed in the usual way: the sum divided by the number of contributors —
mean = (1 + 2 + 4)/3 = 7/3 = 2 1/3
Then the deviations are ...
1 -2 1/3 = -1 1/3 . . . . the absolute value of this is 1 1/3
2 -2 1/3 = -1/3 . . . . . the absolute value of this is 1/3
4 -2 1/3 = 1 2/3 . . . . the absolute value of this is 1 2/3
The mean of these absolute values is their sum divided by the number of them:
(1 1/3 +1/3 +1 2/3)/3 = (3 1/3)/3 = 1 1/9
The MAD of {1, 2, 4} is 1 1/9.
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Your graphing calculator or spreadsheet program may have a function that will calculate this for you.
