Dispersion

Also known as measures of spread.
The dispersion of a data set refers to the form or shape of the distribution
If items are widely dispersed then the averages do not provide a clear summary of the distribution.
In a symmetrical distribution the mean, median and mode all have the same value (or are extremely close).
You can see from the following diagrams that the mean alone is not a good statistic to use when describing a distribution.
SS
It is possible to obtain a better impression of a distribution by measuring the dispersion (or spread) of the values.
Combining the standard deviation with the mean gives a concise and useful description of a distribution.
A measure of dispersion can show whether or not the values in a distribution are clustered closely together or well spread out.

Range

Percentiles

Quartiles

Box Plot

Mean Deviation

Variance

Standard Deviation

Coefficient Of Variation

Standard Score