1. Mean absolute deviation

2. Mean Absolute Deviation
Mean Absolute Deviation is the average distance of each value from their mean.
You will need to find the mean ... use it to work out distances ... then find the mean of those values!

3. Mean Absolute Deviation
Three steps:
1. Find the mean of all values
2. Find the distance of each value from that mean
(subtract the mean from each value, ignore minus signs)
3. Then find the mean of those distances

4. Mean Absolute Deviation
Example:
The Mean Absolute Deviation of 3, 6, 6, 7, 8, 11, 15, 16
Step 1: Find the mean

5. Mean Absolute Deviation
= = 9

6. Step 2: Find the distance of each value from that mean:
Distance from 9 3 6 7 2 8 1 11 15 16

7. Mean Absolute Deviation
Which looks like this:

8. Mean Absolute Deviation
Step 3. Find the mean of those distances: 6, 3, 3, 2, 1, 2, 6, 7

9. Mean Absolute Deviation
Mean Deviation =
  = 30 = 3.75

10. Mean Absolute Deviation
So, the mean = 9 and the mean deviation = 3.75
It tells us how far, on average, all values are from the middle.
In that example the values are, on average, 3.75 away from the middle.