InterQuartile Range( IQR)

              A way to describe data is through quartiles and the interquartile range(IQR)

Above we have some values that are divided into 3 quartiles ranges 

Lower Quartile(Q1) = 14

Median Quartile(Q2) = 22

Upper Quartile(Q3) = 35

A boxplot is used  for easy understanding of  quartiles and outliers in the data

In the above boxplot, we can see the minimum value and three quartile ranges and the max value here

60 may be an outlier for finding  a perfect outlier we set a fence that indicates the outlier in the data

for finding IQR  we have a formula for finding it             

IQR = Q3 - Q1 =35-14

Interquartile range  = 21

Outliers here are defined as observations that fall below Q1 - 1.5 IQR or above Q3 + 1.5 IQR

Lower  Q1  - 1.5(IQR)  =14 - 1.5(21) = -17.5

                                             Upper Q3 + 1.5(IQR) =  35 + 1.5(21) = 66.5                                             - 

Here in this data, the perfect outliers are -17.5, 66.5

The main use of IQR is to find "outliers" in the data

Note: Values should be arranged in ascending order for finding IQR

Hope you understood well, thank you