Note: See Box Chart Examples in the SAS/QC Sample Library.
In the previous example, the OUTLIMITS= data set TURBLIM saved control limits computed from the measurements in Turbine
. This example shows how these limits can be applied to new data. The following statements create the box chart in FigureĀ 17.13 using new measurements in a data set named Turbine2
(not listed here) and the control limits in TURBLIM:
title 'Box Chart for Power Output'; ods graphics on; proc shewhart data=Turbine2 limits=Turblim; boxchart KWatts*Day / odstitle=title; run;
The ODS GRAPHICS ON statement specified before the PROC SHEWHART statement enables ODS Graphics, so the box chart is created by using ODS Graphics instead of traditional graphics.
The LIMITS= option in the PROC SHEWHART statement specifies the data set containing the control limits. By default, this information is read from the first observation in the LIMITS= data set for which
the value of _VAR_
matches the process name KWatts
the value of _SUBGRP_
matches the subgroup-variable name Day
The chart reveals an increase in variability beginning on August 1.
In this example, the LIMITS= data set was created in a previous run of the SHEWHART procedure. You can also create a LIMITS= data set with the DATA step. See LIMITS= Data Set for details concerning the variables that you must provide.