Modeling and Multivariate Methods - SAS

608 Visualizing, Optimizing, and Simulating Response Surfaces Chapter 24
The Simulator
Figure 24.61 Yield Maximum
The maximum Yield is approximately 0.62 at a Time of 0.116 hours and Temperature of 539.92 degrees
Kelvin, or hot and fast. [Your results may differ slightly due to random starting values in the optimization
process. Optimization settings can be modified (made more stringent) by selecting Maximization Options
from the Prediction Profiler pop-up menu. Decreasing the Covergence Tolerance will enable the solution
to be reproducible.]
In a production environment, process inputs can’t always be controlled exactly. What happens to Yield if the
inputs (Time and Temperature) have random variation? Furthermore, if Yield has a spec limit, what percent
of batches will be out of spec and need to be discarded? The Simulator can help us investigate the variation
and defect rate for Yield, given variation in Time and Temperature.
Select Simulator from the Prediction Profiler pop-up menu. As shown in Figure 24.62, fill in the factor
parameters so that Temperature is Normal weighted with standard deviation of 1, and Time is Normal
weighted with standard deviation of 0.03. The Mean parameters default to the current factor values.
Change the number of runs to 15,000. Yield has a lower spec limit of 0.55, set as a column property, and
shows on the chart as a red line. If it doesn’t show by default, enter it by selecting Spec Limits on the
Simulator pop-up menu.