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 NPCHART Statement

## Saving Proportions of Nonconforming Items

 See SHWNP1 in the SAS/QC Sample Library

In this example, the NPCHART statement is used to create a data set that can be read later by the SHEWHART procedure (as in the preceding example). The following statements read the number of nonconforming items from the data set CIRCUITS (see "Creating np Charts from Count Data" ) and create a summary data set named CIRHIST:

```   title 'Subgroup Proportions of Failing Circuits';
proc shewhart data=circuits;
npchart fail*batch / subgroupn  = 500
outhistory = cirhist
nochart;
run;
```

The OUTHISTORY= option names the output data set, and the NOCHART option suppresses the display of the chart, which would be identical to the chart in Figure 37.2. Figure 37.5 contains a listing of CIRHIST.

 Subgroup Proportions of Failing Circuits

 batch failP failN 1 0.010 500 2 0.012 500 3 0.022 500 4 0.012 500 5 0.008 500 6 0.018 500 7 0.034 500 8 0.020 500 9 0.024 500 10 0.018 500 11 0.016 500 12 0.014 500 13 0.014 500 14 0.030 500 15 0.016 500 16 0.036 500 17 0.024 500 18 0.032 500 19 0.008 500 20 0.014 500 21 0.034 500 22 0.024 500 23 0.016 500 24 0.014 500 25 0.030 500 26 0.012 500 27 0.016 500 28 0.024 500 29 0.014 500 30 0.018 500
Figure 37.5: The Data Set CIRHIST

There are three variables in the data set CIRHIST.

• BATCH contains the subgroup index.
• FAILP contains the subgroup proportion of nonconforming items.
• FAILN contains the subgroup sample size.

Note that the variables containing the subgroup proportions of nonconforming items and subgroup sample sizes are named by adding the suffix characters P and N to the process FAIL specified in the NPCHART statement. In other words, the variable naming convention for OUTHISTORY= data sets is the same as that for HISTORY= data sets.