Example 13.37 Computing Process Capability Indices

You can save process capability indices in an OUTLIMITS= data set if you provide specification limits with the LSL= and USL= options. This is illustrated by the following statements:

title 'Control Limits and Capability Indices';
proc shewhart data=Partgaps;
   xchart Partgap*Sample / outlimits = Gaplim2
                           usl       = 270
                           lsl       = 240
                           nochart;
run;

The data set Gaplim22 is listed in Output 13.37.1.

The variables _CP_, _CPL_, _CPU_, and _CPK_ contain the process capability indices. It is reasonable to compute capability indices in this case, since Figure 13.33.7 indicates that the process is in statistical control. For more information, see the section OUTLIMITS= Data Set.