Measures of Spread

Range

One measure of spread is the range. The range is simply the difference between the largest value (maximum) and the smallest value (minimum) in the data.

Example: Find the range of the data set shown below:

75, 80, 90, 94, 96

The range of this data set is 96−75=21. This is telling us the distance between the maximum and minimum values in the data set.

The range is useful because it requires very little calculation, and therefore, gives a quick and easy snapshot of how the data are spread. However, it is limited, because it only involves two values in the data set, and it is not resistant to outliers.