Learn how to calculate the mean absolute deviation ( MAD ) of a data set.

The MAD is the average distance of all of the elements in a data set from the mean of the same data set. You can think of it as how far each piece of information is from the average.

Find the MAD of the number of sunny days a month in Sunnyvale.

**Step 1.**Find the mean

Add up all of the elements and divide this by the number of elements in the data set.

25,15,20,17,22,28,27= 154

154/7 = 22

**Sunnyville has a mean of 22**

**Step 2.**Calculate how far each element is away from the mean and use the absolute value because, distance is always positive.

25-22 = | 3 | 3

15-22 = | -7 | 7

20-22 = | -2 | 2

17-22 |-5 | 5

22- 22 = 0 0

28-22 = | 6 | 6

27-22 = | 5 |

__5__

28

**Step 3.**Divide the total from step 2 by the number of elements in the data set.

28/7 = 4

**So the MAD is 4**

The MAD indicates how spread out your data set is.

A large MAD indicates a data set more spread out relative to the mean.

A small MAD indicates a data set less spread out relative to the mean.