Thanks for your answer
It was hard to find any significance in cluster level with 1 or 0.5 of '-c'.
So FDR was performed.
In optional arguments, is it correct '-m' for mean_FA_skeleton_mask.nii.gz?
Also, it does not seem to be any option for thresholding with voxel number
in FDR.
Thanks,
bsJeong
> That's the problem with cluster-based methods - there's no good way
> of choosing the cluster-forming threshold, or the data smoothing.
> If your data is weak you could try reducing the -c threshold to even
> as low as 1.5 or lower (this is valid in randomise, but not in GRF).
> You could also try FDR - see the FSL manual page for this.
> Cheers.
>
>
> On 15 Mar 2007, at 01:36, bs Jeong wrote:
>
>> Thank you for your recommendation.
>> It sounds everybody can make something with the cluster-based
>> correction.
>> I was not able to find any significant change after either '-c 3'
>> and '-c
>> 2' option with 5000 times permutation.
>> Please let me know what in tstat maps give me suggestion to decide
>> adequate '-c value'.
>> Could you see my t maps?
>>
>> thanks,
>>
>> bsJeong
>>
>>> Hi,
>>>
>>> I would definitely recommend to present some results
>>> corrected for multiple comparisons, rather than going
>>> for any voxel number threshold in your uncorrected
>>> maps.
>>> It looks like you have a lot of significant
>>> uncorrected results for p<0.005, so I am quite
>>> surprised you do not obtain anything with the
>>> cluster-based correction.
>>> What t threshold have you used in your randomise
>>> option -c? You may have chosen a too stringent level.
>>> I would therefore suggest to look at your tstat maps
>>> to find out which -c would seem reasonable to enter...
>>>
>>> Best,
>>> Gwenaelle
>>>
>>>
>>> --- bs Jeong <[log in to unmask]> a écrit :
>>>
>>>> Dear FSLer
>>>>
>>>> I did TBSS analysis.
>>>> But I did not any significant difference between
>>>> groups in cluster level.
>>>> So I'd rather find something in tbss_vox_stat with p
>>>> value or tbss_tstat
>>>> with t value.
>>>> Problem is that so many regions are showed as
>>>> difference btw group even
>>>> though 1-p value is thresholded with 0.9949.
>>>> Is there any method to threshold with consecutive
>>>> voxel number?
>>>>
>>>> Thanks,
>>>>
>>>> bsjeong
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>
>
> ------------------------------------------------------------------------
> ---
> Stephen M. Smith, Professor of Biomedical Engineering
> Associate Director, Oxford University FMRIB Centre
>
> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
> +44 (0) 1865 222726 (fax 222717)
> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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