Box plots A box plot is a diagram which provides a quick visual summary of the distribution of a data set. It makes drawing conclusions easier and is useful for comparing two sets of data.

In the following example, a box plot is used to compare the delay times for airline flights during the Christmas holidays with the delay times prior to the holiday period. The following statements ...

The medians of two box plots are significantly different at approximately the 0.05 level if the corresponding notches do not overlap. For example, in Output 18.3.1, the median for December 20 is ...