Hard to change factors, center points and replicates

[#1]

I am making a design where I want to use the "hard to change" option for three of my four factors for practical reasons, and I want to add a few center points (which will be from historical data) to the design and make replicates of the design points. Is there some way to implement this in JMP while using the "hard" option?

[#2]

This design should not be difficult, as far as you have described it, using DOE > Custom Design.

I would caution you about adding replicates. Replication automatically appears when there are sufficient number of runs above the minimum. You can, though, request a minimum number of replicates, too.

I would also caution about using historical data for the center points. If you just mean the factor levels, that should be no problem. If these levels do not appear in the optimal design, then use discrete numeric factors instead of continuous factors. If you mean to enter historical responses, then you run the risk that something is different during the experiment but you won't know. Besides estimation the center points can also serve as control runs.but only if they are run again in the experiment at the same time as the other runs.

See Help > Books > Design of Experiments. The explanation of custom design in the early part of the guide should make it clear how to handle each of your requests.

[#3]

I am facing a similar challenge: I would like to add (a) centrepoints and (b) space-filling design to an already existing costom design with hard to change factors. The parameters that are difficult to change should not be changed in the space-filling design (b). Unfortunately, the options under the menu "augment design" are not available.