Hi Anderson,

Thanks for you answer. I'd like to be a bit more precise. If I look at the uncorrected p-value for the TFCE results for FA threshold = 0.2 and FA threshold =0.01, I can see good overlap in the region where differences are significant. However after FWE correction, some regions for FA threshold = 0.2 become not significant while they are in the case of FA threshold = 0.01 and vice versa. 
As you said, the TFCE results depends on the support region and so I don't expect for different FA threshold to get the same results but if I have very similar uncorrected p-values, I was wondering how was FWE and size of interested regions are linked. 
Hope that is bit more clear!

Thank you so much!

Giang-Chau

2016-09-29 3:16 GMT-05:00 Anderson M. Winkler <[log in to unmask]>:
Hi Giang-Chau,

The TFCE results are already FWE corrected. Unless you looked into the uncorrected, something should not be done.

All the best,

Anderson


On 29 September 2016 at 03:21, Giang-Chau Ngo <[log in to unmask]> wrote:
Hi Anderson,

Thank you for your quick answer! I understand now. 
Do you think the FWE correction could lead to some differences too since the number of voxels included are different?

Thanks!

All the best,

Giang-Chau

2016-09-28 1:51 GMT-05:00 Anderson M. Winkler <[log in to unmask]>:
Hi Giang-Chau,

The support region of the TFCE (see the original paper) depends on the size of the region one is looking at, which here depends on the FA threshold, so the results can differ.

All the best,

Anderson


On 27 September 2016 at 21:52, Giang-Chau <[log in to unmask]> wrote:
Dear FSL experts,

I have two infants DTI data set and I have run TBSS + randomise (with TFCE) analysis using different FA thresholds (0.1, 0.15, 0.2) therefore different masks.
When looking at the corrected p-value map, I have noticed that some tracts appear significantly (p<0.05) different when using a FA=0.02 but are not when using=0.1 and vice versa. Are the differences in p-value between the different thresholds resulting from the correction of the multiple comparison?

Thank you very much for your time and help!

Giang-Chau