Setting a constraint on 2nd interaction?

Question

Is it possible to set a constraint on a 2nd interaction term? For example, if i have two factors q and r and I know their product is equal to 20, q*r=20, is there a way I can set that as a constraint in the DOE custom design? If not is there a good workaround to get the result I'm hoping to achieve?

Mark_Bailey · Answer

Concur with the latter suggestion above.

shoffmeister · Answer

Generally speaking you should be able to do it using a Disallowed Combinations Script like the following:

The problem I see is that the two factors cannot really be orthogonal (or even close) as long as you restrict the product to be exactly 20. Therefor I assume that JMP will always fail to produce a good design for that problem.

Maybe you might want to treat the two factors as one instead, as the second one is automatically given, after you have chosen the level of the first one. The will always be correlated as long as there is this constraint on the interaction.