Range
What is the range?
- The range is the difference between the highest value and the lowest value
- range = highest - lowest
- For example, the range of 1, 2, 5, 8 is 8 - 1 = 7
- range = highest - lowest
- It measures how spread out the data is
- Ranges of different data sets can be compared to see which is more spread out
- Be careful with negatives
- The range of -2, -1, 0, 4 is 4 - (-2) = 6
How do I know when to use the range?
- The range is a simple measure of how spread out the data is
- The range does not measure an average value
- It should not be used if there are any extreme values (outliers)
- For example, the range of 1, 2, 5, 80 is 80 - 1 = 79
- This is not a good measure of spread
- The range is affected by extreme values
- For example, the range of 1, 2, 5, 80 is 80 - 1 = 79
Examiner Tip
- If asked to find the range in an exam, make sure you show your subtraction clearly (don't just write down the answer).
Worked example
Find the range of the following data.
| 3.4 | 4.2 | 2.8 | 3.6 | 9.2 | 3.1 | 2.9 | 3.4 | 3.2 |
| 3.5 | 3.7 | 3.6 | 3.2 | 3.1 | 2.9 | 4.1 | 3.6 | 3.8 |
| 3.4 | 3.2 | 4.0 | 3.7 | 3.6 | 2.8 | 3.9 | 3.1 | 3.0 |
Range = highest value - lowest value
9.2 - 2.8
The range is 6.4
