Find the mean deviation about median for the following data.
18,23,9,11,26,4,14,21
First arranging data in ascending order4,9,11,14,18,21,23,26 No. of terms n=8 ( even)
Since n is even,
median =(n2)th term,
=(82)th term,
=4th term,
=14
Now, We calculate mean deviation about median
median (M)=14
mean deviation about median =∑|xi−M|8
M.d.=(|4−14|+|9−14|+|11−14|+|14−14|+|18−14|+|21−14|+|23−14|+|26−14|)8
=(|−10|+|−5|+|−3|+|0|+|4|+|7|+|9|+|12|)8
=10+5+3+4+7+9+128
=508
=6.25