The interquartile range shows the range in values of the central 50% of the data. To find the interquartile range, subtract the value of the lower quartile Q1 from the value of the upper quartile ...

Box plots characterize a sample using the 25th, 50th and 75th percentiles—also known as the lower quartile (Q1), median (m or Q2) and upper quartile (Q3)—and the interquartile range (IQR = Q3 ...

Examined here were the accuracy and bias of estimates of whisker length based on box, line, and midgap plots. For each type of graph, a different sample of undergraduates viewed 48 single-plot graphs.