Thanks for your reply, David. The thing is that the *tfce_corrp_tstat* files don't show any significant effect. Any thoughts on to what extent the uncorrected but TFCE based p-maps would indicate that there is indeed an effect, even if the formally corrected p-maps don't show any? I mean, the uncorrected maps show clustered effects at logical locations and therefore look very plausible. Or is TFCE never a surrogate for real multiple comparisons correction? After reading Steve's TFCE paper I think it's not just a cosmetical operation but adds real sensitivity...

On Thu, Apr 26, 2012 at 3:56 PM, David V. Smith <[log in to unmask]> wrote:

Hi Rene,

Those are indeed the uncorrected images. You want to use the ones that end in *_tfce_corrp_tstat. Take a look at the randomise webpage for more information (http://www.fmrib.ox.ac.uk/fsl/randomise/index.html).

Cheers,
David

On Apr 26, 2012, at 9:28 AM, René Besseling wrote:

> Dear FSL users,
>
> I've performed group ICA and group comparison using dual regression. The stage 3 statistics I get include *_tfce_p_tstat*.nii and *tfce_corrp_tstat*.nii maps of (1-p). I'm now a bit at a loss how to interpret the *_tfce_p_tstat*.nii maps; their naming suggests they are uncorrected, however dual regression makes use of permutation testing which would provide multiple comparison correction. Furthermore, the results are threshold-free cluster enhanced (tfce), which suppresses stray (and therefore probably false-positive) significant voxels. I guess this also provides (maybe somewhat informal) control over the Type 1 error. Should I therefore consider the *_tfce_p_tstat*.nii outputs as truly uncorrected or do they deserve more credit?
>
> Best regards,
>
> Rene Besseling