Question

What is Mean Absolute Deviation (MAD)? How do I do it? (Please have an example to show.)

Answer 1

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.