[R] Trouble about the interpretation of intercept in lm models

[Stefano Leonardi]

David Winsemius wrote:
> 
> 
> It would be so *if* you had estimated a saturated model, but you did 
> not. Your fit
> of Y|A values is adjusted for the B values.
> 
Thank you.
What do you exactly mean by "Y|A values is adjusted for the B values"?

And Yes. It works! Using the interaction I got what I expected as intercept.

Thanks
Stefano
> Try instead with lm(Y ~ A * B). You should get intercept (1), main 
> effects(1+2) and
> interaction terms(2) which should total the number of groups. 
> Appropriately combined,
> these estimates will now exactly fit the "raw values".
> 

-- 
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  Stefano Leonardi
  Dipartimento di Scienze Ambientali
  Universita` di Parma                E-mail: stefano.leonardi at unipr.it
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