Find the mean deviation about the median for the data in Exercises.
13, 17, 16, 14, 11, 13, 10, 16, 11, 18, 12, 17
Here the number of observations is 12 which is even. Arranging the data into ascending order, we have 10, 11, 11, 12, 13, 13, 14, 16, 16, 17, 17, 18.
Now, Median
The absolute values of the respective deviations from the median, i.e., |xi – M| are
3.5, 2.5, 2.5, 1.5, 0.5, 0.5, 0.5, 2.5, 2.5, 3.5, 3.5, 4.5
Therefore 
And 
Hence, the mean deviation about the median for the given data is 2.33.
4