The interquartile range is the third quartile (Q3) minus the first quartile (Q1). This gives us the range of the middle half of a data set. ... The IQR gives a consistent measure of variability for skewed as well as normal distributions.

How are quartiles used to measure the variability?

Quartiles are used to calculate the interquartile range, which is a measure of variability around the median. The interquartile range is simply calculated as the difference between the first and third quartile: Q3–Q1. In effect, it is the range of the middle half of the data that shows how spread out the data is.

What does interquartile range tell you?

The interquartile range (IQR) is the distance between the first and third quartile marks. The IQR is a measurement of the variability about the median. More specifically, the IQR tells us the range of the middle half of the data.