DOE with 3 levels for continuous factors

Question

Hi,

We would like to do a DOE with 3 continuous factors. 2 of these should have three levels and 1 should have only two. I didn't find a way to specify more than 2 levels for continuous factors in the custom design platform. I could use the center point, but that also adds a third level for the 3rd factor which should only have 2.
A workaround could be to set them up as discrete numercial and set the three levels we want, but that does not seem to be the best approach...
I'd be grateful for suggestions.

Victor_G · Accepted Answer

Hi @matthias_bruchh,

Enforcing some levels for some of your factors in the design generation is a common DoE topic in the Community.

I see at least two options to get the desired number of levels in your DoE by using Custom design platform :

* Either you specify in the model panel some higher order effects for your factors : for example, specifying up to 2nd order polynomial terms in the model for X1 will create a design with 3 levels for X1,
* Or you could create a design with discrete numeric factors in the Custom Design to "enforce" the number of levels and specific levels you want to include in your design, and switch back the design role of the factors to "continuous" once the datatable is created.

These are the options I already recommended in these discussions :

Number of factor levels in I-Optimal design

Inquiry about Experimental Design with JMP

force levels in DoE

Hope this answer will help you,