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Mar 17, 2017 10:44 AM
(1424 views)

I'm trying to create a model with a 3-way interaction term. I selected the variables and clicked on "cross" per JMP instructions for 2 or more variables. But JMP gives me the following warning:

"The model is missing an effect

X1*X2*X2*X1"

Which is especially odd since what I entered into the model, and what appears in the dialog box, is:

X1

X2

X3

X4

X5

X1*X2*X3

Any thoughts on how to resolve this?

Thanks

1 ACCEPTED SOLUTION

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Mar 17, 2017 10:51 AM
(2835 views)

Solution

If you want the term X1*X2*X3, then you must also include X1*X2, X1*X3, and X2*X3 to maintain the *linear model hierarchy*, even if these lower order terms are not significant.

Learn it once, use it forever!

2 REPLIES

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Mar 17, 2017 10:51 AM
(2836 views)

If you want the term X1*X2*X3, then you must also include X1*X2, X1*X3, and X2*X3 to maintain the *linear model hierarchy*, even if these lower order terms are not significant.

Learn it once, use it forever!

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Mar 17, 2017 10:56 AM
(1416 views)

Ahhh, you're right! I was thinking that only the lower order terms needs to be included. Thanks!