why not a continuous model? what model do you want to use?
Xie, Hong wrote:
> Thanks a lot. This scrip seemly describes F-test or T-test. In my
> study, I want to analyze the correlationship between patient's
> cortical thickness and pain scale (from 0 to 6). After I create data
> table. Qdec automatically put pain scale into continuous variable
> category. Actually, pain scale is ordinal variable, not continuous
> variable. Different correlation model should be used. How should I do
> it by qdec?
> I very appreciate your help.
> Hong Xie
>
> ------------------------------------------------------------------------
> *From:* Douglas N Greve [mailto:greve@nmr.mgh.harvard.edu]
> *Sent:* Mon 1/12/2009 3:11 PM
> *To:* Xie, Hong
> *Cc:* freesurfer@nmr.mgh.harvard.edu
> *Subject:* Re: [Freesurfer] Qdec correlation analyses
>
> Not with QDEC, but you can write your own FSGD, See
>
> https://surfer.nmr.mgh.harvard.edu/fswiki/FsgdExamples
>
> Xie, Hong wrote:
> > Hello,
> > Thank you for answering me. I searched mailing list and read this
> > answer email:
> > /I see that group.levels has four levels. Unfortunately, right now
> > qdec only supports two levels for a discrete factor. One the features
> > in the works is to increase this./
> > /Nick Schmansky
> > Wed, 27 Feb 2008 11:08:10 -0800/
> > Is this question still here? I have a five levels discrete factor. Can
> > I run correlation statistic by Qdec?
> > Thanks again
> > Hong Xie
> >
> > ------------------------------------------------------------------------
> > *From:* Douglas N Greve [mailto:greve@nmr.mgh.harvard.edu]
> > *Sent:* Thu 1/8/2009 4:40 PM
> > *To:* Xie, Hong
> > *Cc:* freesurfer@nmr.mgh.harvard.edu
> > *Subject:* Re: [Freesurfer] Qdec correlation analyses
> >
> >
> > It has to be interpreted as a continuous variable. The test is done
> > using a t-test inside the glm. This reduces to a Pearson if there is
> > only one variable and no intercept (which it is not).
> >
> > doug
> >
> > Xie, Hong wrote:
> > >
> > > Hello, freesurfer group,
> > >
> > >
> > >
> > > I have run qdec for comparing thickness between two groups. When qdec
> > > does a correlation analyses for thickness versus a second variable: 1)
> > > Does the second variable have to be a continuous interval variable or
> > > 2) can the second variable be an ordinal variable with more than 2
> > > levels? In the case of the correlation between two continuous
> > > variable, is the test a Pearson correlation? If 2) is possible, is the
> > > correlation a Spearman correlation?
> > >
> > > Thank for your help,
> > >
> > >
> > >
> > > Hong Xie
> > >
> > >
> ------------------------------------------------------------------------
> > >
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> >
>