The BOXPLOT Procedure

Example 25.4 Creating Notched Box-and-Whiskers Plots

The following statements use the flight delay data of Example 25.1 to create box-and-whiskers plots with notches:

title 'Analysis of Airline Departure Delays';
title2 'Using the NOTCHES Option';
proc boxplot data=Times;
   plot Delay*Day /
      boxstyle = schematicid
      nohlabel
      notches;
   id Reason;
   label Delay = 'Delay in Minutes';
run;

The notches, requested with the NOTCHES option, measure the significance of the difference between two medians. The medians of two box plots are significantly different at approximately the 0.95 confidence level if the corresponding notches do not overlap. For example, in Output 25.4.1, the median for December 20 is significantly different from the median for December 24.

Output 25.4.1 Notched Side-by-Side Box-and-Whiskers Plots