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Discussions

Solve problems, and share tips and tricks with other JMP users.
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Xinghua
Level III

Why can't I detect curvature (nonlinearity) in DOE in JMP?

In Minitab, if the factors in the DOE have center points, the curvature will be directly tested (i.e. nonlinearity, p<0.05 indicates that the curvature is significant), but there seems to be no such function in JMP?

12 REPLIES 12
MRB3855
Super User

Re: Why can't I detect curvature (nonlinearity) in DOE in JMP?

Hi @Xinghua : to add to @P_Bartell , I would not use those leverage plots if there is curvature in your model that is unaccounted for (as @Victor_G  outlined); and as you can see from the leverage plots, the center point is clearly higher than the factorial points (-1, 1) indicating curvature.

Xinghua
Level III

Re: Why can't I detect curvature (nonlinearity) in DOE in JMP?

Thank you.

I also found that the Y value corresponding to the center point seems to be higher, but unfortunately there is no value to judge (such as the p value of nonlinearity test). After all, judging by eyes is not very accurate and difficult to convince client.

MRB3855
Super User

Re: Why can't I detect curvature (nonlinearity) in DOE in JMP?

Hi @Xinghua : Indeed; and as you can see from the above responses, there are ways to get the test (p-values etc) you need for curvature.

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