Mean Deviation
Lecture 12
Mean Deviation
The mean deviation indicates how the individual observation is far from the central part (average) of the data.
Definition
The arithmetic mean of the absolute values of
deviations from their mean (or median) is called mean deviation or absolute
mean deviation. The mean deviation measures the average distance between each
value of the data and its mean.
The mean deviation from sample data can be calculated as:
When the data is expressed in the frequency distribution,
then the mean deviation can be computed as:
A relative measure of dispersion based on mean
deviation is called the coefficient of mean deviation. It is defined as the ratio
of the mean deviation to the mean (or median) of the data concerned.
Example 4.4: Find the mean deviation and coefficient of
mean deviation from the following data.
8, 10, 12, 16,
18, 20
Solution: Compute the mean and then deviate from each
value
Example 4.5: Find the mean deviation
and coefficient of mean deviation for the following frequency distribution.
|
Class |
10 – 14 |
14 – 18 |
18- 22 |
22 - 26 |
26 - 30 |
30 - 34 |
34 - 38 |
|
Frequency |
5 |
9 |
17 |
15 |
13 |
19 |
11 |
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