Dear JMP & Community,
I'm trying to set up a Custom DOE where one of the factors has three levels, and each level of this factor MUST be present in each random block only once.
Situation:
We have a DOE where we know there will be 4 continuous variables that can range between low and high values. We have an additional factor that is a three-level categorical factor. The DOE must be grouped into random blocks of size 3 (this is due to limitations on the number of runs that can be performed in a day, 3 morning and 3 afternoon) -- of course the total number of runs is also a multiple of 3. The last factor, X5, has 3 levels, L1, L2, L3 which physically represent 3 locations of a sample within a drying oven. These locations are left, center, and right.
The researcher runs batches in groups of three and each batch gets a position within the drying oven, left, right, or center. Researchers can run up to six batches in a day, so the random blocks are of size 3 (3 morning and 3 afternoon). Whenever three batches are made, all three positions get used. For example, run 1 might go in position L2, run 2 in position L3, and run 3 in position L1. One of the things being tested (in combination with the other factors) is whether the location within the drying oven is having an impact on the outcome.
Problem:
The problem I'm facing is how to force that when JMP generates a DOE, that it ensures each of the 3 levels occurs once in each random block, yet be randomly assigned to the runs. In the screen shot below, I think it helps to show the problem. For the first six runs for the random blocks 1 & 2, the order of X5 is L2, L2, L3 & L1, L1, L3. Obviously, this can't occur in the design because L1, L2, and L3 refer to left, center, and right positions in the oven and can can only be used once within a random block. so the order of X5 should be something like L1, L3, L2 and L3, L2, L1 for random blocks 1 & 2. I still need each level to be randomly assigned to the runs, but that each level appears only once within each random block. I do not think that adding a blocking factor is the right way, but perhaps I'm wrong.
In the DOE model, I am also interested in testing all main effects from X1-X5 and all 2nd order interactions between all factors.
Possible solution:
The only way I can come up with at the moment is to generate a DOE with the four continuous factors and a DOE with the one 3-level categorical factor. Each has the same number of runs and then joining the tables together by matching the column "Random Block". But, when I do that, each run from the four factor DOE is repeated 3 times because of the different levels of categorical factor from the other DOE. This isn't what I want, either. If I click the Drop Multiples from the Main Table, then I go back to the original number of runs, but the ordering of X5 is almost always the same: L2, L3, L1. Also, I don't think the 18 runs will be enough to also capture the 2nd order interaction of X5 with the other four factors. I believe I'll need more like 30 runs total to be able to capture all 2nd order interactions. This still doesn't quite capture what I want, because it's repeating the same run for all three levels within a random block.
If anyone has had a similar issue and figured out how to overcome this, I'm very interested in learning how you did this. Or, if there is a proper methodology within JMP to achieve this, that is also something I'm interested in learning.
Thanks for your interest and input!,
DS
