What are the formulas for the upper and lower quantiles?

The general formula for the upper quartile is Q₃ = 3 / 4 (n + 1), where "Q₃" denotes the upper quartile and "n" indicates the total number of values in a sample set, while the formula for the lower quartile is Q₁ = 1 / 4 (n + 1), where "Q₁" represents the lower quartile. The upper and lower quartiles are measures in statistics.

In a sample population containing a set of data values sorted in increasing order, a "median" refers to the middle value. The upper quartile is the median of the upper half, while the lower quartile is the median of the lower half of the set. By subtracting the lower quartile from the upper quartile, the interquartile range is calculated.