Saving Proportions of Nonconforming Items

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.

For more information, see "OUTHISTORY= Data Set" .

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