# Quartile Deviation

Quartile deviation is another measure of dispersion. It is given by

Relative measure of dispersion based on quartiles is the coefficient of quartile deviation (Q.D.).

Example

The quartiles of a variable are 45, 52 and 65, respectively. Find its quartile deviation and coefficient of quartile deviation.

Solution

Given:

*Q*_{1}= 45,*Q*_{2}= 52,*Q*_{3}= 65# Merits

- It is easy to calculate.
- It can be easily understood.
- It is not affected by the extreme values.
- It has a special utility in measuring variation in case of frequency distribution with open-end classes at both ends.

# Demerits

- It is not based on all the observations.
- It is not the representative value of data.
- It is not capable of algebraic treatments.
- It is affected by sampling fluctuations.