Dear experts,
As much as I appreciate that FDR control is a conceptual breakthrough in
the theory of multiple comparisons, I have what I think are fundamental
questions (which are probably already addressed in the literature):
When I am searching a continuous space (such as a time-frequency map) for
significant effects, how do I interpret small patches (spanning say 2-3
elements/pixels/voxels/vertices in each dimension) of significant effects
that show up? As discoveries, they are as valid as a big blob that might
show up. When the FDR control is done element-wise, it is clear that the
cluster-wise FDR could be high. Since we are actually going after clusters
or rather peaks in a functional map of some kind, what does voxelwise or
element-wise FDR control actually mean? It doesn't seem appropriate to
take the mass-univariate approach for a time-frequency map without any
consideration of the topology. What does it even mean to assign
activations to time-frequency elements when the underlying quantity is
inherently continuous? Am I missing something? FDR control seems to be
done routinely with functional imaging data.
Thanks and Regards,
Hari
--
Hari Bharadwaj
|