It is
defined as the arithmetic average or mean of the deviation of various items of a
series computed from mean or median.
Or
It is the
average difference between the items of a distribution and the mean or median of
that series.
For an
individual series
Mean
deviation from mean or average = 
Mean
deviation from mean=
Example:
To calculate the mean deviation from mean
|
Marks |
Frequency (f) |
Mid value (x) |
fx |
 |
 |
f |
|
0-10 |
5 |
5 |
25 |
27 |
22 |
110 |
|
10-20 |
8 |
15 |
120 |
27 |
12 |
96 |
|
20-30 |
15 |
25 |
375 |
27 |
2 |
30 |
|
30-40 |
16 |
35 |
560 |
27 |
8 |
128 |
|
40-50 |
6 |
45 |
270 |
27 |
18 |
108 |
|
|
n = |
|
 |
|
|
|
Mean deviation =
=
=
9.44
Download pdf file of mean deviation
