Example 12.4 Optimal Design Using an Augmented Best Design

[See OPTEX4 in the SAS/QC Sample Library]This example is a continuation of Example 12.2.

You can specify a set of points that you want to be included in the final design found by the OPTEX procedure by using the AUGMENT= option in the GENERATE statement to specify a data set that contains a design to be augmented.

In this case, you can try to speed up the search for a 50-run design by first finding an optimal 25-run design and then augmenting that design with another 25 runs, as shown in the following statements:

proc optex data=a seed=36926;
    model AFR|EGR|SA@2 AFR*AFR EGR*EGR SA*SA;
    generate n=25 method=detmax;
    output out=b;

proc optex data=a seed=37034;
    model AFR|EGR|SA@2 AFR*AFR EGR*EGR SA*SA;
    generate n=50 method=detmax augment=b;
run;

The result (see Output 12.4.1 and Output 12.4.2) is a design with almost 100% D-efficiency and A-efficiency relative to the best design found by the first attempt. However, this approach is not much faster than the original approach, since the run time for the DETMAX algorithm is essentially linear in the size of the design (see the section Memory and Run-Time Considerations.