Dear SPM folks,
Could someone explain to me why and how the initial p-threshold affects SVC and/or 3dClustSim correction?
As for SVC, part of what I am confused about is that I thought SVC would calculate the Resels (resolution elements) within the (inclusive) masked area, and then correct the p-value based on random field theory. But then this would mean that the initial p-threshold would have nothing to do with the SVC-correction, which is clearly not the case in my experience.
For instance, when I use the initial threshold of p = 0.001 uncorrected, and then do SVC correction, the peak significance values are the same as when I used initial p = 0.05 uncorrected. But when I use initial p = 0.05 FWE corrected, the same cluster would not even show up in both before and after SVC correction.
As for 3DClustSim, I would like to know what are the differences in calculation compared to SVC in SPM? And pros and cons?
Any answers and/or references are highly appreciated!
Best,
Frances
|