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Hi Jeanette, I wasn't expecting a perfect match, and not even a perfect match between 2*p(Ttest) and p(Ftest). I just wasn't expecting as big a difference as I got (see summary measures below). Especially the corrected p values differ no end: minima of 1(?!) versus 0.07. With respect to raw p-values, the robust minumum raw p in the Ftest is more than 70 times higher than the Ttest's. Although the F fits T² perfectly in every voxel, the TFCE Tstats are higher than the TFCE Fstats. I was just wondering if this has something to do with the bi-directional quality of F statistics: could it make the data less spatially consistent? And secondly, could an Ftest lead to larger clusters in permutations / by chance? Many thanks for your help, Emma --------------------------------------------- SUMMARY MEASURES: Corrp: fslstats -R Ftest: 0.000000 to 0.000000 Ttest:. 0.000000 to 0.923800 Corrp: fslstats -r Ftest: 0.000000 to 0.000000 Ttest: 0.019400 to 0.897010 Raw p: fslstats -R Ftest: 0.000000 to 0.991200 Ttest: 0.000000 to 0.998600 Raw p: fslstats -r Ftest: 0.098129 0.363770 Ttest: 0.567205 0.991610 TFCE: fslstats -R Ftest: 0.000000 160431.156250 Ttest: 0.000000 183206.484375 TFCE: fslstats -r Ftest: 3850.347656 56792.628906 Ttest: 366.412964 153343.828125