Dear Prof. Gaser,
I am getting familiar with the TFCE toolbox that you developed for VBM statistical analysis (http://dbm.neuro.uni-jena.de/tfce/). I have a question regarding the choice of permutation methods: Draper-Stoneman or Freedman-Lane.
My experimental design is ANCOVA (comparing two groups on VBM and controlling for several covariates (age, TIV, etc). I am using the "Full factor" model in SPM12 statistical design. According to the explanation, the Freedman-Lane method seems more appropriate ("Draper-Stoneman which is the preferred permutation method if no nuisance variables exist").
Yet, when I use TFCE toolbox, it selects the Draper-Stoneman by default. When I ran the TFCE for both methods, the Freedman-Lane method gave more results at the significance thresholds of FDR<0.05 and p<0.001 uncorrected, while Draper gave more results at the significance threshold of FWE<0.05.
I wonder which TFCE permutation method makes more sense for ANCOVA? And why did the two methods behave differently across the three significance thresholds (I suppose that the differences should be consistent)?
Many thanks!
Best regards,
Haobo Zhang
Lecturer
School of Psychology and Sociology
Shenzhen University
China
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