Range of a data set - Definition and Examples

In statistics, the range of a data set is the difference between the highest value and the lowest value in the data set.

Example #1

Albert earned the following scores in his math tests:

Chapter 1 test: 90

Chapter 2 test: 85

Chapter 3 test: 70

Chapter 4 test: 98

Chapter 5 test: 81

The highest score is 98 and the lowest score is 81.

To find the range, subtract the lowest value from the highest value.

Range  = 98 - 81 = 17

The range in Albert's score is 17

Example #2

Sarah earned the following scores in her math tests:

Chapter 1 test: 90

Chapter 2 test: 91

Chapter 3 test: 89

Chapter 4 test: 90.5

Chapter 5 test: 89.5

The highest score is 91 and the lowest score is 89.

To find the range, subtract the lowest value from the highest value.

Range = 91 - 89 = 2

The range in Sarah's score is 2

How useful is the range of a data set? Why do we need it?

The range of a set of data is a measure of variation. The range in the example #2 is much smaller than the range in example #1. This means that the scores do not vary a lot or are more consistent. This could mean that Sarah has a tendency to be always prepared to take a test.