Quartiles divide a rank-ordered data set into four equal parts.
The interquartile range (IQR) is a measure of variability, based on dividing a data set into quartiles.
Due to its resistance to outliers, the interquartile range is useful in identifying when a value is an outlier.
Formula to calculate interquartile range.
Q3 is the median of the upper quartile.
Q1 is the median of the lower quartile.
Suppose the median of the upper quartile is 50 and the median of the lower quartile is 25, calculate the interquartile range.
Therefore, the IQR is 25.