# Comparing data

**The range**

The range is described as the lowest value subtracted from the highest value. This is not an average but the measure of a spread. The range can be used to assess the values in a data set as the the more spread out the range, the less consistent the data and the closer together the range the lower and more consistent or reliable the values are.

For example:

1.62, 1.41, 1.35, 1.20, 1.15

The range is calculated as:

= 1.62 – 1.15 = **0.47**

**Finding the interquartile range**

The interquartile range is represented as the data which is the middle half of the data and if used when there are outliers within data. It is calculated as follows:

Interquartile range = upper quartile – lower quartile

Upper quartile = the data values in the last quarter of the list

Lower quartile = the data values in the first quarter of the list

For example:

12.1, 14.0, **15.3**, 15.4, 15.4, 15.6, 15.7, 15.7, **16.1**, 16.7, 17.0

Upper quartile = 15.3

Lower quartile = 16.1

Inter quartile range = 16.1 – 15.3 = 0.6