Example 11.7 Merging Columns in a Comparative Pareto Chart

[See PARETO14 in the SAS/QC Sample Library]This example is a continuation of Example 11.4 and illustrates a method for merging the columns in a comparative Pareto chart.

Suppose that controls for metallization were introduced on Wednesday. To show the effect of the controls, the columns for Monday and Tuesday are to be merged into a column labeled Before Controls, and the remaining columns are to be merged into a column labeled After Controls. The following statements introduce a format named CNTLFMT that merges the levels of Day:

proc format;
   value cntlfmt   1-2 = 'Before Controls'
                   3-5 = 'After Controls' ;

The following statements create the chart shown in Output 11.7.1:

ods graphics on;
title 'Pareto Analysis by Process and Control Phase' ;
proc pareto data=Failure7;
   vbar Cause / class       = ( Process Day )
                freq        = Counts
                last        = 'Miscellaneous'
                scale       = count
                catleglabel = 'Failure Causes:'
                nohlabel
                nocurve
                nlegend ;
   format Day cntlfmt. ;
   label  Day = 'Status of Controls for Metallization';
run;
ods graphics off;

Output 11.7.1 Merging Classification Levels

The levels of Day are determined by its formatted values, 'Before Controls' and 'After Controls'. By default, the order in which the columns are displayed is determined by the internal values. In this example, there are multiple distinct internal values for each level, and the procedure uses the internal value that occurs first in the input data set.