XCHART Statement: SHEWHART Procedure

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:

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 15.98.

Figure 15.101 contains a partial listing of 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:

proc shewhart data=Partgaps;
   xchart Partgap*Sample / outhistory = Gaphist2
                           stddeviations
                           nochart;
run;

Figure 15.102 contains a partial listing of 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.