Yes.
Cheers.
On 12 Feb 2008, at 18:56, Jiansong Xu wrote:
> Thanks. Is the df dependent on the number of subjects? For example,
> I have 16 subjects in one group, I did the analysis of correlation
> between FA and RT, is the dr = 15?
>
>
> Best
>
> Jiansong Xu, M.D., Ph.D.
> Associate Research Scientist
> Dept. of Psychiatry
> Yale School of Medicine
>
> Connecticut Mental Health Center, Room S-100
> 34 Park St.
> New Haven, CT 06519
>
>
>
>
>
>
>
> On Feb 12, 2008, at 12:45 PM, Gwenaëlle DOUAUD wrote:
>
>> Hi again!
>>
>> --- Jiansong Xu <[log in to unmask]> a écrit :
>>
>>> Dear Friends:
>>>
>>> In fMRI, when we state stats threshold, we usually
>>> say; voxel level
>>> threshold < .01 (or .05), not corrected, extent
>>> threshold p < .05
>>> corrected. In tbss, if I use randomise -c to correct
>>> multiple
>>> comparisons, the voxel level threshold is determined
>>> by the t value
>>> after the -c option (my understanding). My question
>>> is how to
>>> calculate the t value corresponding to voxel level p
>>> < .05 or p < .01?
>> http://faculty.vassar.edu/lowry/tabs.html#t
>> (one-tailed P-value). Then all you need to know are
>> the degrees of freedom in your statistical model...
>> Alternatively, you can just report in your manuscript
>> the t-value you have chosen (it's always arbitrary
>> anyway, even if 0.05 or 0.01 are somehow more
>> evocative than 2.4 for instance) and the DOF.
>>
>> Cheers,
>> Gwenaelle
>>
>>
>>
>> _____________________________________________________________________________
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>
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