Ok screw it, I went and watched a video on it
You calculate MAD by working out the absolute value that each data point is away from the mean
To do so, subtract each point from the mean, and then you don't care if the result is positive or negative, you just write it as positive
So
4 - 7 = -3, deviation is 3
4 - 7 = -3, deviation is 3
4 - 7 = -3, deviation is 3
5 - 7 = -2, deviation is 2
8 - 7 = 1, deviation is 1
9 - 7 = 2, deviation is 2
9 - 7 = 2, deviation is 2
9 - 7 = 2, deviation is 2
9 - 7 = 2, deviation is 2
9 - 7 = 2, deviation is 2
Now, you add up all the deviations, and divide them by the number of points of data you have, so
(3 + 3 + 3 + 2 + 1 + 2 + 2 + 2 + 2 + 2)/10, or simply
22/10
So the MAD is 2.2
I think
