Dear Karsten and Claus,
just a small comment -
>Dear Claus,
>
>>) What is the difference between multiple regression and multiple
>>regression with constant? Which one should I use when I want to asses
>>the effects of two predictors (scores of questionnaires) on contrast images
>>(results of fixed effects analysis)
>>
>>
>
>I would recommend the multiple regression with a constant term, since this is the most general way to do a regression.
>It's according to y = b1*x1 + b2*x2 + constant , which is the usual equation for a linear regression analysis.
>
>
the multiple regression without cste might be correct if one already
work on some differences .. let's say we have a factorial design A1 A2
B1 B2 and we compute A1-A2 and and B1-B2 at the 1st level. In this case
the global effect (cste) is removed by subtraction and the regression
model at the second level should be performed without cste, right?
Of course in the case of Claus, given the results he got, I suspect that
it wasn't the case I depicted hereabove.
Best
- Cyril
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