You are correct.
On 01/09/2014 02:18 PM, yaya ya wrote:
> Dear Doug,
>
> I am sorry. It is my first time to post the message in this way. I am
> now used to it:)
>
> The results from the contrast 0 0 1 -1 did not survive the multiple
> comparision corrections. In other words, I guess that it should imply
> that I could try DOSS.
>
> If my thought is wrong, please feel free to let me know.
>You can specify a mask for an ROI when you run mri_glmfit. But that
> By the way, is it possible to do SVC (small volume correction) using
> an anatomical image from a particular brain region, which is the
> conventional way to improve statistical power?
means you have to run your own simulation to do the correction.
doug
>
> Thanks, again.
>
>
> On Thu, Jan 9, 2014 at 6:23 PM, Douglas N Greve
> <mailto:greve@nmr.mgh.harvard.edu> <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>> wrote:
>
>
> Please remember to post to the list. For the 0 0 1 -1 contrast,
> did any results survive multiple comparisons correction? If so,
> then at least the voxels in that region cannot be used with DOSS.
> I'm not sure why the patter was opposite between the two
> contrasts. I could mean that there is a nonlinear relationship
> with age.
>
> doug
>
>
> On 01/09/2014 03:54 AM, yaya ya wrote:
>
> Dear Greve,
>
> Thank you very much for your response. I am now a little more
> clear, although I still have some further questions.
>
> According to your suggestion, I just tried to test whether
> there is a difference between group age. I included age as a
> continuous variable in qdec. After running, I got the results
> arising from the contrast 0 0 1 -1 (which is called does the
> thickness-age correlation differ between two groups?). That
> is, the results revealed the thinner in some brain areas. But
> when I checked the results relating to the comparision of
> groups (1 -1 0 0 ), the results were the same expect the
> opposite pattern. That is, the results became thicker in the
> same region.
>
> Does this imply that there is an age effect? It means I could
> not use DOSS to do analysis, right?
>
> Best,
> Lickey
>
>
> On Thu, Jan 9, 2014 at 12:32 AM, Douglas N Greve
> <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>
> <mailto:Freesurfer@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.edu>>> wrote:
>
>
> On 01/08/2014 04:28 PM, yaya ya wrote:
> > Dear Freesurfer experts,
> >
> > I have a question about cortical thickness analysis using
> freesurfer.
> > Since I don't know how to post my question in freesurfer
> mailing
> > list, that is why I am writing to you to get some help.
> Hopefully, my
> > email will not cause you any troubles.
> Thanks for posting to the list.
> >
> > My question is : When I compared thickness from two
> groups (a
> patient
> > group and a healthy contrl group), that is say I got the
> thinner
> in a
> > subdivision of a particular brain region in patients
> than that in
> > controls. But when I added age as a nusiance factors
> (not in the
> > continuous covariate because I want to control for or
> regress
> out the
> > age effect) in qdec, the results changed. In the same
> region, the
> > thickness became thicker in the patients than that in the
> controls. I
> > have no idea what happened. Which of them do I need to
> trust?
> The age
> > between two groups has been matched.
> It depends on several things. It might be that there is an
> interaction
> between group and age. Try testing for a difference
> between the age
> slopes of the two groups. If there is no difference, then
> re-run using
> DOSS (DOSS was removed from QDEC so you'll have to create
> an FSGD file
> and use mri_glmfit).
> >
> > In addition, when I do FDR correction on the results,
> the min in the
> > threshold jumped to more than 5 , making all the clusters
> disappear. I
> > think this correction is too high, unabling the genious
> effects to
> > show up. How to deal with it?
> Try using a cluster correction instead of FDR.
> doug
>
> >
> > By the way, our lab's IT staffs install the lastest released
> > freesurfer. But when I use the qdec, I could not find
> the option of
> > DODS and DOSS, as discussed in the mailing list. I am
> wondering
> if it
> > has been deleted in this new version.
> >
> > I really appreciate your help in advance.
> >
> > Best,
> > Lickey
> >
> >
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>
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>
> --
> Douglas N. Greve, Ph.D.
> MGH-NMR Center
> greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>
> <tel:617-724-2358 <tel:617-724-2358>>
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> --
> Douglas N. Greve, Ph.D.
> MGH-NMR Center
> greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>
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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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