Quartile: Quartiles are the values that divide an ordered data set into four (approximately) equal parts. It is only possible to divide a data set into exactly four equal parts when the number of data of values is a multiple of four.
There are three quartiles. The first, the lower quartile (Q1), divides off (approximately) the lower 25% of data values. The second quartile (
Q2Q2
) is the median. The third quartile, the upper quartile (
Q3Q3
), divides off (approximately) the upper 25% of data values.