Dear Douglas, thank you very much for you kind reply.
In the paper I have 3 groups (2 diseases and 1 controls).
I have performed cortical thickness analysis among groups, individuating
relevant difference in the posterior regions.
Next, for one group, I have used qdec to individuate statistically
significant regions where NPS test scores and thickness were correlated. 3
nuisance factors was also added to regressor. All results were corrected for
multiple comparisons by using a pre-cached cluster-wise Monte-Carlo
Simulation.
qdec analysis results have individuated a "composite region" (superior
parietal cortex and precuneus) where NPS correlated with thinning.
Now, if I understand, I should extract the mean thickness from superior
parietal cortex and precuneus and I should perform a linear regression (and
partial correlation) with an other statistical program (SPSS for example).
Is there a better way to perform a regression the most possible similar to
qdec computation?
Stefano
----Messaggio originale----
Da:
greve@nmr.mgh.harvard.edu
Data: 4-dic-2013 17.35
A:
<stdp82@virgilio.it>, <freesurfer@nmr.mgh.harvard.edu>
Ogg: Re:
R: Re: [Freesurfer] Linear regression
On 12/02/2013 03:14 PM,
stdp82@virgilio.it wrote:
> Tank you very much.
>
> A-Do you
mean the partial correlation coeff (PCC) at each voxel
> averaged over
region?
> Finally a linear regression is done between cortical thickness
of a
> composite region and NPS. However the authors discuss every
individual
> region as related to disease. So a table with partials
correlations of
> individuals ROIs with NPS seems useful to support the
discussion.
What did you do in the paper? The reviewer mentions a "composite
region". Did you average the thickness over that region and then do the
regression with NPS?
>
> B- I'd like to obtain the covariance
matrix of the regression made
> between cortical thickness, group and
covariates. How can I do it?
> I'm not sure what you mean. Would this be a
different matrix for each
> vertex?
> I cite the referee: "The
authors must provide the covariance matrix of
> the regression made
between cortical thickness, group and covariates
> as supplementary
information in order to increase the value of the
> results."
Sorry, I
don't understand what the reviewer is asking for.
doug
>
> I
don't have Matlab for mri_glmfit_pcc matlab.
>
>
Stefano
>
>
>
>
> ----Messaggio
originale----
> Da: greve@nmr.mgh.harvard.edu
> Data: 2-dic-2013
20.47
> A: <freesurfer@nmr.mgh.harvard.edu>
> Ogg: Re:
[Freesurfer] Linear regression
>
>
> On 12/02/2013 02:22 PM,
stdp82@virgilio.it wrote:
> > Hi list,
> >
> > I have
some questions, please.
> >
> > I performed linear regression
by qdec to find the regions where the
> > cortical thinning correlates
with neuropsychological test (NPS),
> > taking in account 3 nuisance
factors.
> >
> > A- I individuated some posterior regions and
now I'd like to build a
> > table with partials correlations of
individuals ROIs with NPS. How can
> > I obtain the values for each
region?
> Do you mean the partial correlation coeff (PCC) at each voxel
averaged
> over region? You can get PCC maps using the mri_glmfit_pcc
matlab
> command. You can then do the averaging over region using
mri_segstats.
> >
> > B- I'd like to obtain the covariance
matrix of the regression made
> > between cortical thickness,group and
covariates. How can I do it?
> I'm not sure what you mean. Would this be a
different matrix for each
> vertex?
> >
> > C- Is there
a specific reference for qdec?
> No, it is just a GLM so any GLM reference
will do.
> >
> > Thank you very much,
> >
>
>
> > Stefano
> >
> >
> >
>
>
> >
> >
_______________________________________________
> > Freesurfer mailing
list
> > Freesurfer@nmr.mgh.harvard.edu
> >
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
>
> --
> Douglas N. Greve, Ph.D.
> MGH-NMR Center
>
greve@nmr.mgh.harvard.edu
> Phone Number: 617-724-2358
> Fax:
617-726-7422
>
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--
Douglas N. Greve, Ph.D.
MGH-NMR
Center
greve@nmr.mgh.harvard.edu
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