Dear FS experts

One of our reviewers would like to know whether the FDR procedures as implemented in FS on one hand and as implemented in SPM on the other hand are comparable.

In FS, I think FDR is based on the height threshold (FDRp) and it is outside of the random Gaussian field theory framework, isn't it?

For SPM, it has been shown that the FDR procedure based on height threshold (FDRp) is not appropriate in the random Gaussian field theory framework (Chumbley et al., 2010; Chumbley and Friston, 2009, both published in NeuroImage). Therefore, in SPM8 FDRc (based on the cluster volume) was implemented and should be preferred over FDRp, isn't it?

Therefore, we conclude that it is not possible to use a comparable parametric multiple comparisons correction procedure in FS and SPM.

Do the nonparametric procedures (SnPM for SPM and Monte Carlo simulations in FS) are comparable?

Or is it impossible to get any comparable procedure due to the fact that a voxel is in 3D (as in SPM), whereas a vertex is on a 2D manifold (as in FS)?

Thanks in advance Regards Jürgen Hänggi

---------------------------------------------------------------------------- Jürgen Hänggi, Ph.D. Division Neuropsychology Institute of Psychology University of Zurich Binzmuehlestrasse 14, PO Box 25 8050 Zurich, Switzerland 0041 44 635 73 97 (phone office) 0041 76 445 86 84 (phone mobile) 0041 44 635 74 09 (fax office) BIN 4.D.04 (office room number) j.haenggi[at]psychologie.uzh.ch (email) http://www.psychologie.uzh.ch/neuropsy/ (website) http://www.juergenhaenggi.ch (private website)

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