|Continuous Group Variables|
By default, the PLOT statement treats numerical group variable values as discrete values and spaces the boxes evenly on the plot. The following statements produce the box plot in Figure 25.9:
ods graphics off; title 'Box Plot for Power Output'; proc boxplot data=Turbine; plot KWatts*Day; run;
The labels on the horizontal axis in Figure 25.9 do not represent 10 consecutive days, but the box-and-whiskers plots are evenly spaced.
In order to treat the group variable as continuous, you can specify the CONTINUOUS or HAXIS= option when producing traditional graphics. Either option produces a box plot with a horizontal axis scaled for continuous group variable values. (ODS Graphics does not support a continuous group axis.)
title 'Box Plot for Power Output'; proc boxplot data=Turbine; plot KWatts*Day / turnhlabels continuous; run;
Note that the tick values on the horizontal axis represent consecutive days and that no box-and-whiskers plots are displayed for days when no turbine data were collected.