Dear Gracian (and SnPM users),
> I'm performing a regression study with Statisticl non-Parametric
> Mapping (SnPM5 for SPM5 package). I'm wonder if is possible to
> design a model with more than one covariate of interest (i.e.
> perform a multiple regression model).
Unfortunately, the answer is "No". But there is quite a bit of debate
whether it is appropriate to include multiple covariates in a regression
analysis in SnPM. As you may know, SnPM randomly shuffles observations
to generate the probability distribution for a statistical test,
assuming that there is no association between your image data and the
covariate. However this assumption may or may not hold when you have two
or more covariates, because the association between the images Y and the
covariate X could be influenced by an additional covariate Z in your
model. That is the reason why SnPM doesn't have such a study design.
-Satoru
Satoru Hayasaka PhD ----------
Assistant Professor, Public Health Sciences & Radiology
Wake Forest University School of Medicine
(ph) +1-336-716-8504 / (fax) +1-336-716-0798
(email) shayasak _at_ wfubmc _dot_ edu
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