Modeling and Multivariate Methods - SAS

Chapter 24 Visualizing, Optimizing, and Simulating Response Surfaces 621
Noise Factors (Robust Engineering)
Figure 24.75 Comparison of Distributions With and Without Noise Factors
The histograms show that there is much more variation in Hardness when the noise factor was not included
in the analysis.
It is also interesting to note the shape of the histogram when the noise factor was included. In the
comparison histograms above, note that the With Noise Factor distribution only has data trailing off in one
direction. The predictions are skewed because Hardness is at a minimum with respect to SILICA, as shown
in Figure 24.76. Therefore, variation in SILICA can only make HARDNESS increase. When the non-robust
solution is used, the variation could be transmitted either way.
Figure 24.76 Profiler Showing the Minima of HARDNESS by SILICA
Other Platforms
Noise factor optimization is also available in the Contour Profiler, Custom Profiler, and Mixture Profiler.