This is a statistic which shows how the number of a series cluster around the mean and to what extend they diverge from the mean. There are three measures of dispersion:

• Range
• Variance
• Standard deviation

RANGE

This is the difference between the two extremes numbers, the highest and the lowest. It is calculated as:

RangeR=Highest number-lowest number

R= Xn-X0

Example: Consider the series: 30, 70, 60, 130, 150, 190. Calculate its range.

Solution

Range(R) = 190-30=160.