Fundamentals of Statistics contains material of various lectures and courses of H. Lohninger on statistics, data analysis and here for more.

Interquartile Range

As with the mean and the standard deviation, distributions can also be described by the median and a range of fractiles around the median. The interquartile range (IQR) in particular is used to describe the dispersion of the data.

The interquartile range (IQR) is defined as the range between the first and the third quartile. Please note that the IQR contains exactly 50 % of the data within the distribution.