Thanks for the responses so far! The thread Chris has linked to is actually the one I was refering to as well :-) The reason I asked is that there is no real discussion concerning uncorrected voxel-threshold IN COMBINATION with corrected cluster-threshold (corrected as provided by SPM output, so no "corrected" pre-definied value like k > 10).
In the salmon poster, the authors "argue that relying on standard statistical thresholds (p < 0.001) and low minimum cluster sizes (k > 8) is an ineffective control for multiple comparisons." In a study of ~ 15 subjects and standard resolution (after normalization) the FWE-corrected cluster-threshold should be something to ~ 50 - 200 voxels, so much higher.
The SCAN paper by Bennett and colleagues (2009) does provide any definite answer about corrected cluster-threshold either. They say "It is possible to use the combination of a P-value and a cluster size in a principled way, but it requires computing the proper values for each and every analysis. The cluster size criteria can change quite substantially from dataset to dataset. Further, it can be the case that required cluster sizes become so large that legitimate results with a smaller volume are missed."
So, what about this combination of voxel-p = .001 and cluster-p = .05 FWE? Are the limitations (different cluster-threshold in different studies) acceptable or not?
Best,
Gabor
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