Hi,
I am pretty new to using JMP and statistics in my designs, but am thoroughly enjoying learning about it!
My question is about how to choose ranges for your factors. Say I am designing a process with a factor that can run between 1-100. I also "expect" the optimal range to be around the 15-20 mark. (Assume the desirability is maximized at that range, as in quadratic increasing from 0-20 then decreasing beyond that).
My concern is that when I design a DOE, I get a scatter of low, middle, high conditions, (0, 50, 100), but even the 50 in this case is expected to be very high and most likely undesirable.
- Is there a reason to tighten the range so that the center point is close to expectation or will JMP still provide the optimal condition regardless? (And I would therefore just be giving up explored range without gaining anything)
- Ex. Range = 0-30 vs. Range = 0-100
- Is there a time and place when and when not to tighten or widen ranges?
- Ex. Definitive Screen (Where factors are being explored for significance) vs. optimization DOEs
Some reading has led me to believe you want the largest ranges possible so that the model can effectively "fall off" on both sides of an optimum, but I wonder if you can still be too wide...
