You can plot the residuals from the forecasting model by using PROC SGPLOT and a WHERE statement.

1. Use the OUTRESID option or the OUTALL option in the PROC FORECAST statement to include the residuals in the output data set.

2. Use a WHERE statement to specify the observation type of ’RESIDUAL’ in the PROC GPLOT code.

The following statements add the OUTRESID option to the preceding example and plot the residuals:

   proc forecast data=past interval=month lead=10
                 out=pred outfull outresid;
      id date;
      var sales;
   run;
   
   proc sgplot data=pred;
      where _type_='RESIDUAL';
      needle x=date y=sales / markers;
      xaxis values=('1jan89'd to '1oct91'd by qtr);
   run;

The plot of residuals is shown in Figure 15.5.

Figure 15.5 Plot of Residuals