quartile

Definition

One of the three numbers (values) that divide a range of data into four equal parts. The first quartile (also called 'lower quartile') is the number below which lies the 25 percent of the bottom data. The second quartile (the 'median') divides the range in the middle and has 50 percent of the data below it. The third quartile (also called 'upper quartile') has 75 percent of the data below it and the top 25 percent of the data above it. See also interquartile range and percentile.