Besides being a less sensitive measure of the spread of a data set, the interquartile range has another important use. Due to its resistance to outliers, the interquartile range is useful in identifying when a value is an outlier. The interquartile range rule is what informs us whether we have a mild or strong outlier.

What does the 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.

Why is IQR better than range?

Interquartile range gives another measure of variability. It is a better measure of dispersion than range because it leaves out the extreme values. It equally divides the distribution into four equal parts called quartiles.