Modeling and Multivariate Methods - SAS

Chapter 24 Visualizing, Optimizing, and Simulating Response Surfaces 595
The Simulator
Run the Simulation
Specify the number of runs in the simulation by entering it in the N Runs box.
After factor and response distributions are set, click the Simulate button to run the simulation.
Or, use the Make Table button to generate a simulation and output the results to a data table.
The table contains N Runs rows, simulated factor values from the specified distributions, and the
corresponding response values. If spec limits are given, the table also contains a column specifying whether a
row is in or out of spec.
The Simulator Menu
Automatic Histogram Update toggles histogram update, which sends changes to all histograms shown
in the Profiler, so that histograms update with new simulated values when you drag distribution handles.
Defect Profiler shows the defect rate as an isolated function of each factor. This command is enabled
when spec limits are available, as described below.
Defect Parametric Profile shows the defect rate as an isolated function of the parameters of each factor’s
distribution. It is enabled when the Defect Profiler is launched.
Simulation Experiment is used to run a designed simulation experiment on the locations of the factor
distributions. A dialog appears, allowing you to specify the number of design points, the portion of the
factor space to be used in the experiment, and which factors to include in the experiment. For factors
not included in the experiment, the current value shown in the Profiler is the one used in the
experiment.
The experimental design is a Latin Hypercube. The output has one row for each design point. The
responses include the defect rate for each response with spec limits, and an overall defect rate. After the
experiment, it would be appropriate to fit a Gaussian Process model on the overall defect rate, or a root
or a logarithm of it.
A simulation experiment does not sample the factor levels from the specified distributions. As noted
above, the design is a Latin Hypercube. At each design point, N Runs random draws are generated with
the design point serving as the center of the random draws, and the shape and variability coming from
the specified distributions.
Spec Limits
shows or edits specification limits.
N Strata is a hidden option accessible by holding down the Shift key before clicking the Simulator popup
menu. This option allows you to specify the number of strata in Normal Weighted. For more
information also see “Statistical Details” on page 625.
Set Random Seed is a hidden option accessible by holding down the Shift key before clicking the
Simulator popup menu. This option allows you to specify a seed for the simulation starting point. This
enables the simulation results to be reproducible, unless the seed is set to zero. The seed is set to zero by
default. If the seed is non-zero, then the latest simulation results are output if the Make Table button is
clicked.