I was wondering if anybody is able to help with (any one of) these questions? That would be really helpful, as I could not find an answer on the wiki.
Many thanks in advance! On 26 March 2013 20:44, Tudor Popescu <tud...@gmail.com> wrote: > Hi everyone, > > > My QDEC analysis ran into an error message that seems to be a "classic" > (and, so far, it seems unsolved), from mri_concat, which I've described in > a separate message, just sent. > > > I have, however, more theoretical questions about QDEC, which I hope some > kind soul will help me with: > > - why does QDEC only provide the volume of *subcortical* structures under > StatsDataImport/aseg.volume, when the automatic GM/WM segmentation is done > for the entire brain, not just for subcortical regions? > > > - how are the volume measurements provided in aseg.volume different from > the ones done obtained with a VBM analysis? > > > > - why is *volume *the result of *segmentation *(aseg.volume) whereas > *thickness > *derives from *parcelation *(rh.aparc.thickness)? Is it not the case that > both operations (segmentation+parcellation) are necessary to calculate > volume as well as thickness? > > - how is a QDEC thickness analysis different from a regular AN(C)OVA in > which you are interested in main and interaction effects of the IVs on the > DV? I ask this because some of the questions that appear in QDEC's Analysis > Results tab – e.g. "is the correlation between (DV) and (IV) different from > zero?" – would not (I think) be directly answerable by an ANOVA > > > > - would the same type of ANOVA done by QDEC be doable by extracting the > values of the DV for each subject (using e.g. *aseg.volume*) and then > doing the ANOVA in e.g. SPSS? If so, when would you do one versus the other? > > > > - why is it that only continuous factors (e.g. age) can be taken in the > analysis as nuisance factors, when discrete variables (e.g. gender) might > also be irrelevant for a particular analysis and thus belong to the > Nuisance Factor list? > > > > Many thanks in advance!! > > Tudor >
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