| SPECHART Statement |
- SPECHART < / options> ;
The SPECHART statement produces an SPE chart based on a principal components model computed by the MVPMODEL procedure. In a Phase I analysis, the SPE statistics are computed by the MVPMODEL procedure and read from the HISTORY= data set. In a Phase II analysis, the SPE statistics are computed by the MVPMONITOR procedure from information about the principal components model which is specified in the LOADINGS= data set.
You can specify the following options after a slash (/):
- ALPHA=value
specifies the probability used to compute control limits for the SPE chart. If you specify ALPHA=
, the control limits are computed so that the probability is that the SPE statistic exceeds its control limits. The value of can range between 0 and 1. By default, is 0.05. - CONTRIBUTIONS <(contribution-options)>
-
creates a contribution plot for each point outside the control limits of the SPE chart. You can specify the following contribution-options in parentheses following the CONTRIBUTIONS option:
- MAXNPLOTS=n
specifies the maximum number, n, of contribution plots produced. When n is less than the number of points outside the control limits, contribution plots are produced for the first n out-of-control points.
- MAXNVARS=n
specifies that only the n contributions with the greatest magnitudes be displayed in the contribution plots. For each out-of-control point, the n variables that contribute the most at that point are displayed. By default, all variable contributions are displayed.
- EXCHART
specifies that an SPE chart be created only when one or more points lie outside the control limits.
- NOCHART
suppresses creation of the SPE chart. You typically specify the NOCHART option when you use the OUTTABLE= option to save results to an output data set. You can also use the NOCHART option along with the CONTRIBUTIONS option to produce contribution plots for out-of-control points without displaying the SPE chart.
- NPANELPOS=n
- NPANEL=n
-
specifies the number of horizontal axis plotting positions per panel of the SPE chart. A panel is defined as a screen or page. You typically specify the NPANELPOS= option to display more points on a panel than the default number, which is 50.
You can specify a positive or negative number for n. The absolute value of n must be at least 5. If n is positive, the number of positions is adjusted so that it is approximately equal to n and so that all panels display approximately the same number of positions. If n is negative, no balancing is done and each panel (except possibly the last) displays approximately n positions.
- OUTTABLE=SAS-data-set
creates an output SAS data set that saves the information plotted on the SPE chart, including the SPE statistic values and control limits. See the section OUTTABLE= Data Set for a description of the OUTTABLE= data set.
Note: This procedure is experimental.