Yes.On May 10, 2009, at 8:51 PM, Mark Bailey wrote: Is JMP centering the variables? On May 10, 2009, at 3:39 PM, Michael Bailey wrote: I am confused about the meaning of the intercept term in jmp 7 in a particular context (more below), because its value doesn't match up with what I think it should.
The context is this: A dependent variable, Y, and (at least) two predictors, X1 and X2, and their interaction. If I regress Y onto X1, X2, and X1-cross-X2, the regression coefficients for X1, X2, and the interaction all make sense (and the main effects are calculated by jmp using deviation scores for X1 and X2). However, the intercept does not match what I get when I do this regression the long way (namely, by creating deviation scores for X1 and X2 and taking their product to implement the interaction). Nor does it match the intercept when the raw variables (as opposed to the deviation scores) are analyzed.
Can anyone tell me what is going on and what the Y-intercept in this context means?
Mark
They hate you if you're clever, and they despise a fool ("Working Class Hero" - John Lennon)
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