The interquartile range abbreviated IQR is just the width of the box in the box-and-whisker plot. InterQuartile Range IQR When a data set has outliers or extreme values we summarize a typical value using the median as opposed to the mean. When a data set has outliers variability is often summarized by a statistic called the interquartile range which is the difference between the first and third quartiles.
In descriptive statistics the interquartile range IQR also called the midspread middle 50 or Hspread is a measure of statistical dispersion being equal to the difference between 75th and 25th percentiles or between upper and lower quartiles IQR Q 3 Q 1.
And they are denoted by Q1 Q2 and Q3 respectively. The interquartile range abbreviated IQR is just the width of the box in the box-and-whisker plot. It is used for the statistical calculations of set of data which is divided into 4 equal parts. These values are quartile 1 Q1 and quartile 3 Q3.