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liliconcom

3rd power parameter DOE

Hi JMP ers,

I have 4 factors and try to make a model with main effects, interactions, 2nd order and 3rd order power.

I make design with recomended optimality criteria. When i checked color map correlations i can always see x1 and x1*x1*x1 correlation near to 1. How can make a DOE that does not have this problem?

Analytics

DOE

Re: 3rd power parameter DOE

I tried but got same correlation again.
Did you check your correlation picture? Do i miss something diffrent?

Re: 3rd power parameter DOE

Ella,

What you are seeing is a result of the coding of values for the factors. -1^3 = -1, 1^3 = 1

So if you use "actual values" you will see the correlation matrix without those terms correlated.

Re: 3rd power parameter DOE

i got same picture with real values:(

Re: 3rd power parameter DOE

correlation between

x1, x1*x1*x1 - 0.92

x2, x2*x2*x2 - 0.93 etc.

Re: 3rd power parameter DOE

The X^3 vs X plot has a correlation of 0.916 and the density ellipse is elongated. Find 4 points on that curve that are not correlated. I don't think you can do it. Those terms will always be correlated.

For a contrast, I have also included a plot of X^2 vs. X. The correlation is -0.019 and the density ellipse is almost circular. You can get correlations close to zero between these terms.

Re: 3rd power parameter DOE

I'm sorry, my understanding is that you will always get that correlation due to the coding that goes on "behind the scenes". What I meant to say, AFAIK, the x and x^3 will actually not be correlated if the appropriate designs selected and the actual values are used. The correlation matrix will always show the correlation due to the coding.

Re: 3rd power parameter DOE

I spoke to a JMP DOE developer yesterday (JMP summit) and he confirmed the plots would always show the correlation, but in actuality with the correct design, there is no correlation.

Re: 3rd power parameter DOE

First I made custom Design with d optimality for 2nd order model and augmented Design with I Optimality for 3rd order model. Is it right ?

Re: 3rd power parameter DOE

AFAIK, in the custom design platform, as long as you select Necessary (vs. If Possible), JMP will create a design that will allow for estimation of those effects.

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