Saving Summary Statistics

XCHART Statement

Saving Summary Statistics

See SHWXCHR in the SAS/QC Sample Library

In this example, the XCHART statement is used to create a summary data set that can be read later by the SHEWHART procedure (as in the preceding example). The following statements read measurements from the data set PARTGAPS and create a summary data set named GAPHIST:

   title 'Summary Data Set for Gap Widths';
   proc shewhart data=partgaps;
      xchart partgap*sample / outhistory = gaphist
                              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 42.2.

Figure 42.5 contains a listing of GAPHIST.

Summary Data Set for Gap Widths

sample	partgapX	partgapR	partgapN
1	270	35	5
2	258	25	5
3	248	24	5
4	260	39	5
5	273	29	5
6	260	21	5
7	259	37	5
8	248	37	5
9	260	28	5
10	255	19	5
11	268	36	5
12	253	36	5
13	273	29	5
14	275	22	5
15	257	24	5
16	269	41	5
17	249	36	5
18	264	31	5
19	258	25	5
20	248	36	5
21	248	30	5

Figure 42.5: The Summary Data Set GAPHIST

There are four variables in the data set GAPHIST.

SAMPLE contains the subgroup index.
PARTGAPX contains the subgroup means.
PARTGAPR contains the subgroup ranges.
PARTGAPN contains the subgroup sample sizes.

Note that the summary statistic variables are named by adding the suffix characters X, R, and N to the process PARTGAP specified in the XCHART statement. In other words, the variable naming convention for OUTHISTORY= data sets is the same as that for HISTORY= data sets.

If you specify the STDDEVIATIONS option, the OUTHISTORY= data set includes a subgroup standard deviation variable rather than a subgroup range variable, as demonstrated by the following statements:

   title 'Summary Data Set with Subgroup Standard Deviations';
   proc shewhart data=partgaps;
      xchart partgap*sample / outhistory = gaphist2
                              stddeviations
                              nochart;
   run;

Figure 42.6 contains a listing of GAPHIST2.

Summary Data Set with Subgroup Standard Deviations

sample	partgapX	partgapS	partgapN
1	270	12.6293	5
2	258	10.2225	5
3	248	10.6771	5
4	260	14.2302	5
5	273	11.2027	5
6	260	8.7178	5
7	259	13.3791	5
8	248	13.5093	5
9	260	12.2270	5
10	255	7.8102	5
11	268	16.2327	5
12	253	15.0333	5
13	273	10.6536	5
14	275	8.2765	5
15	257	10.3923	5
16	269	14.8829	5
17	249	14.8661	5
18	264	12.0623	5
19	258	8.8882	5
20	248	13.0384	5
21	248	12.0000	5

Figure 42.6: The Summary Data Set GAPHIST2

The variable PARTGAPS, which contains the subgroup standard deviations, is named by adding the suffix character S to the process PARTGAP.

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

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