
Quartiles Just as one median divides the data into two subgroups, three quartiles divides the data into 4 quarters. The three quartiles are normally represented by the points Q_{1}, Q_{2}, Q_{3} The lower quartile is denoted by Q_{1} and the upper quartile by Q_{3}. The second quartile Q_{2} is the same as the median. Positions of the Quartile Lower Quartile Q_{1} (25 th percentile) : (n+1)/4 Upper Quartile Q_{3} : 3(n+1)/4 The difference between the upper and the lower quartile value is called the Interquartile range Example
