Susan, I am using JMP for my dissertation, and I need to explain mathematically exactly how I arrive at my solutions (using JMP). I obtained the book you referenced, but did not find "step shortening" in this rather dense book. In a very respected source of statistical methods, The NIST Engineering Statistics Handbook [2], I attempted to solve using JMP the example provided there. That example is by the originator of the desirability method (Derringer and Suich 1980 [1]). Using JMP, I could not get the same result provided there. My research problem has all continuous factors. Maybe you could please try it and see what you get. But most importantly, could you please provide a reference scientific paper for the method JMP uses for desirability, or at least the page numbers in the Dennis and Schnabel book that explains the mathematical method used to compute desirability for multiple factors. Thanks so much.
[1] Derringer, G., and Suich, R., (1980), "Simultaneous Optimization of Several Response Variables," Journal of Quality Technology, 12, 4, 214-219.
[2] 5.5.3.2.2. Multiple responses: The desirability approach