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Dear Chris, On Sun, 29 Sep 2013 17:04:13 -0600, Chris Madan <[log in to unmask]> wrote: >Thanks again for the responses! > >On Sun, Sep 29, 2013 at 3:37 PM, Christian Gaser < >[log in to unmask]> wrote: > >> Dear Chris, >> >> On Wed, 25 Sep 2013 22:36:34 -0600, Chris Madan <[log in to unmask]> >> wrote: >> >> >Thanks Christian! >> > >> >Two more questions, if you don't mind: >> > >> >(1) If a cluster is significant at p<.05-FWE, without TFCE, is it fair to >> >assume that it should still be significant with the TFCE? From my >> >understanding of the TFCE, anything that is already significant with TFCE >> >should still be significant, but previously subthreshold, but broad, >> >clusters can be 'enhanced' by the TFCE to also be significant (e.g., Smith >> >& Nichols, 2009, Fig 1, seems to show this). However, I have a contrast >> >that has some suprathreshold clusters at p<.05-FWE (no TFCE), but with the >> >TFCE nothing is significant at even p<.001-uncorrected. Does this sound >> >plausible...? (It may be of relevance, I did not scan the whole brain in >> >this study, but only a slab.) >> If you use very low initial voxel thresholds (e.g. P<0.05 uncorrected) it >> often happens that you obtain a few very large clusters that are >> significant at the cluster level after correction for multiple comparisons. >> In that case TFCE may not result in any significant results, because the >> initial voxel threshold is too low. >> > >This makes sense to me, but I am still not clear on how/if results voxels >that are significant at p<.05 with FWE correction are no longer significant >at even a lenient threshold of p<.001, uncorrected, after the TFCE is >applied. I guess my question is more of, "is something not working >correctly, or is this something that would be expected. In that case I need to see the results in the glass brain to get an idea whether this is correct or not. Best, Christian > > >> >> > >> >(2) Is it possible to do the TFCE with a small volume correction? I >> >understand that this may not be currently implemented since the TFCE >> >distribution is based on the scanned area, and this distribution would >> then >> >need to only be based on the SVC area. >> You can apply SVC if you replace your mask.img/hdr file with a new mask >> defining your SVC-ROI. I will try to implement this in the new TFCE toolbox >> release. >> > >Great, thanks for pointing this out! > >~ Chris >