Hi Carolyn,

from you longitudinal qdec table you can create one that qdec can use by simply manually concatenating the first two collumns with a ".long." in the middle

tpid.long.baseid

and call that column "fsid" in the first row. This will instruct qdec to load the data from the longitudinal directories of this subject. However, Qdec will not understand that these data points come from the same subject. It will assume these are 6 different subjects. It is really only to load the data and investigate. All I am saying is that you cannot really do any longitudinal statistics with a single subject and only a few time points. If you want to use other statistical tools (note we also have Linear Mixed Effects Models in Matlab), you can use asegstats2table and aparcstats2table with the --qdec-long flag (passing the longitudinal qdec table). This will collect the stats values from your time points into a single csv table.

Best, Martin

On 06/08/2016 01:36 PM, Carolyn Drobak wrote:

So if these aren't useful for only 1 subject, what would be the best way to look at data over multiple scans for just the one subject?

On Mon, Jun 6, 2016 at 2:12 PM, Martin Reuter <mreuter@nmr.mgh.harvard.edu mailto:mreuter@nmr.mgh.harvard.edu> wrote:

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 <mailto: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 <tel:%2B1-617-724-5652>
Web  :http://reuter.mit.edu  


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