Hi Carolyn,

not sure what you are asking. You want to do statistics on N=1 subject ?

Anyway, in order to use QDEC, you'd have to reduce the longitudinal data (thickness, measured at different time points) to a single number: the slope of a linear fit. This is called the 2-stage-approach.

Or you skip Qdec and do a Linear Mixed Effects model directly.

Either approach only makes sense if you have a bunch of subjects (per group).

Best, Martin

Ps info on longituidnal statistics:
https://surfer.nmr.mgh.harvard.edu/fswiki/LongitudinalStatistics

On 06/06/2016 09:45 AM, Carolyn Drobak wrote:

Hello,

I have six scans for a single subject. I have performed "group analysis," but wish to use longitudinal data analysis. In particular, I was able to get a base for the subjects, so can view in freeview and all of that. My issue arises when I try to use QDEC. Because QDEC can't use my long.qdec.table.dat file, nor does it like my cross.qdec.table.dat file. The problem seems to be that I only have one base, i.e. one subject. Is there some way to run analysis on this so I can still get all the statistics I want (mostly interested in cortical thickness) using just my one subject?

I'm still fairly new to FS, but have done the large majority of the tutorials, so am pretty sure I'm not just messing up my files here.

Thanks,

CMD

On Mon, Jun 6, 2016 at 9:40 AM, Carolyn Drobak <carolyn.drobak28@gmail.com> wrote:

Hello,

I have six scans for a single subject. I have performed "group analysis," but wish to use longitudinal data analysis. In particular, I was able to get a base for the subjects, so can view in freeview and all of that. My issue arises when I try to use QDEC. Because QDEC can't use my long.qdec.table.dat file, nor does it like my cross.qdec.table.dat file. The problem seems to be that I only have one base, i.e. one subject. Is there some way to run analysis on this so I can still get all the statistics I want (mostly interested in cortical thickness) using just my one subject?

I'm still fairly new to FS, but have done the large majority of the tutorials, so am pretty sure I'm not just messing up my files here.

Thanks,

CD

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-- 
Martin Reuter, PhD
Assistant Professor of Radiology, Harvard Medical School
Assistant Professor of Neurology, Harvard Medical School
A.A.Martinos Center for Biomedical Imaging
Massachusetts General Hospital
Research Affiliate, CSAIL, MIT
Phone: +1-617-724-5652
Web  : http://reuter.mit.edu 

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