Hi Gang,
As far as conjunction analyses are concerned, can you please comment on the two analysis pathways described below that differ in WHEN cluster-extent thresholding is implemented?
It seems to me that method 2 would be overly conservative and would presume that false positives would occur in the same voxel for tests 1 and 2. Is it really necessary to do cluster-extent thresholding after the individual voxel-wise tests? Or does one carry out that step only at the end, on the voxels that spatially overlap for test 1 AND test 2.
1. Voxel-wise thresholding for statistical test #1
2. Voxel-wise thresholding for statistical test #2
3. Identifying spatial overlap among above-threshold voxels for tests 1 and 2.
4. Cluster-wise thresholding on the spatial overlap map
OR
1. Voxel-wise thresholding for statistical test #1, followed by cluster-wise thresholding
2. Voxel-wise thresholding for statistical test #2, followed by cluster-wise thresholding
3. Identifying spatial overlap among above-threshold voxels for tests 1 and 2.
4. Cluster-wise thresholding on the spatial overlap map
Best,
Christine
