). Then
> >> >> you have a paired t-test, whereas mri_glmfit with qdec would be doing
> >> >> an unpaired t-test. I think preproc has an option to calculate within
> >> >> subject differences for a paired t-test with mri_glmfit as well. As
> >> >
rences between
>> groups, the unpaired t-test may be more appropriate.
>>
>> > Subject: Re: [Freesurfer] qdec thickness and repeatability
>> > From: ni...@nmr.mgh.harvard.edu
>> > To: bell0...@umn.edu
>> > Date: Fri, 20 Feb 2009 15:15:10 -0500
>&g
paired t-tests are more sensitive than unpaired t-tests,
> >> and are generally more appropriate when you make within subject
> >> comparisons. On the other hand, if you intend your exercise to be a
> >> test for the likelihood of false positive differences between grou
ect comparisons. On the other hand, if you intend your
exercise to be a test for the likelihood of false positive
differences between groups, the unpaired t-test may be more
appropriate.
> Subject: Re: [Freesurfer] qdec thickness and repeatability
> From: ni...@nmr.mgh.harvard.edu
&g
the likelihood of false positive differences between groups,
the unpaired t-test may be more appropriate.
> Subject: Re: [Freesurfer] qdec thickness and repeatability
> From: ni...@nmr.mgh.harvard.edu
> To: bell0...@umn.edu
> Date: Fri, 20 Feb 2009 15:15:10 -0500
> CC: freesurfer@n
comparisons. On the other hand, if you intend your exercise to be a
test for the likelihood of false positive differences between groups,
the unpaired t-test may be more appropriate.
> Subject: Re: [Freesurfer] qdec thickness and repeatability
> From: ni...@nmr.mgh.harvard.edu
>
differences between
groups, the unpaired t-test may be more appropriate.
> Subject: Re: [Freesurfer] qdec thickness and repeatability
> From: ni...@nmr.mgh.harvard.edu
> To: bell0...@umn.edu
> Date: Fri, 20 Feb 2009 15:15:10 -0500
> CC: freesurfer@nmr.mgh.harvard.edu
>
> The
The two methods are very different. In the method described on the
thickness repeatability page, its computing a mean and stddev of the
thickness for your group. This a direct and easily interpretable
measure, but doesn't give you a statistical measure (but you could do
that on your own with some
