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UCHART Statement |
See SHWUCHR in the SAS/QC Sample Library |
In this example, the UCHART statement is used to create a summary data set containing the number of nonconformities per unit. This data set can be read later by the SHEWHART procedure (as in the preceding example).
A department store receives boxes of shirts containing 10, 25,
or 50 shirts. Each box is inspected, and the total number of defects
per box is recorded. The following statements create a SAS data set
named SHIRTS2, which contains the total defects per box for 20 boxes:
data shirts2; input box flaws nshirts @@; datalines; 1 3 10 2 8 10 3 15 25 4 20 25 5 9 25 6 1 10 7 1 10 8 21 50 9 3 10 10 7 10 11 1 10 12 21 25 13 9 25 14 3 25 15 12 50 16 18 50 17 7 10 18 4 10 19 8 10 20 4 10 ;
A listing of SHIRTS2 is shown in Figure 41.8.
The variable BOX contains the box number, the variable FLAWS
contains the number of flaws in each box, and the variable
NSHIRTS contains the number of shirts in each box.
To evaluate the quality of the shirts, you should report
the average number of defects per shirt. The
following statements create a data set containing the
number of flaws per shirt and the number of shirts per box:
title 'Average Defects Per Tee Shirt'; proc shewhart data=shirts2; uchart flaws*box / subgroupn =nshirts outhistory=shrthist nochart; run;
The SUBGROUPN= option names the variable in the DATA= data set whose
values specify the number of inspection units
per subgroup.
The OUTHISTORY= option names an output data set containing the
number of nonconformities per inspection unit and the number
of inspection units per subgroup.
A listing of SHRTHIST is shown in Figure 41.9.
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There are three variables in the data set SHRTHIST.
Note that the variables containing the numbers of nonconformities per inspection unit and subgroup sample sizes are named by adding the suffix characters U and N to the process FLAWS specified in the UCHART statement. In other words, the variable naming convention for OUTHISTORY= data sets is the same as that for HISTORY= data sets.
For more information, see "OUTHISTORY= Data Set" .
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