I'm using SPM8 r4290.

I am confused as to the meaning/what SPM is doing when you do/do not use FWE. For example, for the attached output, I used FWE p = 0.05 with threshold = 0. The cluster that survived the FWE correction has a pFWE = 0.01, p_uncorrected = 0.198- what does this mean?

For other analyses, I've first tried FWE p = 0.05, did not obtain any results, then did not choose FWE and set p = 0.001. The results showed clusters with pFWE < 0.05; why didn't they survive the initial FWE p = 0.05 correction? Does it mean something different when FWE is not used, but there are clusters with pFWE < 0.05?

Thank you,


Julie E. McEntee, M.A., C.C.R.P.
Senior Research Program Coordinator
Department of Psychiatry- Neuroimaging
Johns Hopkins University School of Medicine
600 N. Wolfe St./ Phipps 300
Baltimore, MD 21287
Phone: 410-502-0468
Fax: 410-614-3676