Brief notes on the definitions, importance and properties of Dispersion

Literally, dispersion means deviation, difference or spread of certain values from their central value. In relation to statistical series, it means, deviations of various items of the series from its central value.


1. According to AX. Bowley, “Dispersion is the measure of variation of the items.”

2. According to Brooks and Dicks, “Dispersion is the degree of the variation of the variable about a central value.”


3. According to Spiegal, “The degree to which numerical data tend to spread about an average value is called variation or dispersion of the data.”

Importance of Dispersion

1. Dispersion can control the various conclusions drawn from central tendency.

2. Dispersion measures the inequalities in the distribution of income and wealth.

3. Dispersion can evaluate the average profit, average sales, average cost etc. in industry, trade or business.


4. It is used to control price and output.

5. It removes the defects of the averages and presents doubtful conclusions in their true form.

Properties of Dispersion

1. It should be rigidly defined and free from any ambiguity.

2. It should be simple to follow.


3. It should be easy for computation and free from complicated procedure of calculations.

4. It should be based on all the items of the series.

5. It should be capable of further algebraic treatment.

6. It should be greatly affected by the values of extreme items of a series.


7. It should not be affected by fluctuations of sampling.