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Can a Doehlert design for 3 factors be set up in JMP?

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Staff

JMP will not create a Doehlert design automatically, but you really shouldn't be able to create one automatically. The Doehlert design is actually just a name given to the points formed when simplex optimization has found an optimum condition. Therefore, one does not really "plan" for this design. It results when the simplex has reached an optimum point and circles around the optimum. Those resulting "circling points" are called a Doehlert design with the center of the space being the optimum according to the simplex. The Doehlert design is then analyzed as if it were a planned design by using regression. This results in a model, something that you do not typically get with simplex optimization.

For three factors a typical Doehlert design would look like this:

 Exp # X1 X2 X3 1 0 0 0 2 1 0 0 3 0.5 0.866 0 4 0.5 0.2887 0.8165 5 -1 0 0 6 -0.5 -0.866 0 7 -0.5 -0.2887 -0.8165 8 0.5 -0.866 0 9 0.5 -0.2887 -0.8165 10 0 0.5774 -0.8165 11 -0.5 0.866 0 12 -0.5 0.2887 0.8165 13 0 -0.5774 0.8165

You can easily just take this design and transform these coded units to your natural units. Without doing the simplex optimization though, I do not know how you would know where to place your "0" point of this design.

If your question is if JMP can analyze a Doehlert design, the answer is YES! It is just regression and you use Fit Model.

Now if your question is if JMP can do simplex optimization, the answer is not directly. A JMP script would need to be built and I believe there might even be one in the community downloads area.

I hope this helps.

Dan Obermiller
3 REPLIES 3
Staff

JMP will not create a Doehlert design automatically, but you really shouldn't be able to create one automatically. The Doehlert design is actually just a name given to the points formed when simplex optimization has found an optimum condition. Therefore, one does not really "plan" for this design. It results when the simplex has reached an optimum point and circles around the optimum. Those resulting "circling points" are called a Doehlert design with the center of the space being the optimum according to the simplex. The Doehlert design is then analyzed as if it were a planned design by using regression. This results in a model, something that you do not typically get with simplex optimization.

For three factors a typical Doehlert design would look like this:

 Exp # X1 X2 X3 1 0 0 0 2 1 0 0 3 0.5 0.866 0 4 0.5 0.2887 0.8165 5 -1 0 0 6 -0.5 -0.866 0 7 -0.5 -0.2887 -0.8165 8 0.5 -0.866 0 9 0.5 -0.2887 -0.8165 10 0 0.5774 -0.8165 11 -0.5 0.866 0 12 -0.5 0.2887 0.8165 13 0 -0.5774 0.8165

You can easily just take this design and transform these coded units to your natural units. Without doing the simplex optimization though, I do not know how you would know where to place your "0" point of this design.

If your question is if JMP can analyze a Doehlert design, the answer is YES! It is just regression and you use Fit Model.

Now if your question is if JMP can do simplex optimization, the answer is not directly. A JMP script would need to be built and I believe there might even be one in the community downloads area.

I hope this helps.

Dan Obermiller
Community Trekker

Thanks DanO. That is helpful indeed.

However, I did not find the simplex optimization script in the JMP community downloads area so as to use it for generating Doehlert designs for 4 or 5 factors...

Staff