Dear Elsa, > I am analyzing data in SPM8 and I was wondering whether the FWE corrected p-value involves Bonferroni corrected values or is it based on something else? I have read some very old related posts related to this topic here and I am a bit confused. Is the FWE p value based on random field theory, Bonferroni or does it use both Bonferroni and RFT methods? > How is the FWE corrected p value calculated in SPM 8? For voxelwise correction, SPM uses random field theory to calculate a corrected p value. This is generally more lenient than the Bonferroni correction because the topology of the data are taken into account (the smoothness; i.e. that nearby voxels are not independent). SPM also calculates the Bonferroni value and reports the value (random field theory or Bonferroni-corrected) which is more lenient (which is usually the random field corrected one). See spm_P.m. Hope this helps! Best regards, Jonathan -- Dr. Jonathan Peelle Department of Neurology University of Pennsylvania 3 West Gates 3400 Spruce Street Philadelphia, PA 19104 USA http://jonathanpeelle.net/