Hi,

I was trying to figure out if there is any way to determine the exact size at which clusters becomes significant given a specified significance, and it appeared from the mc-corrected overlay that in this overlay the clusters do not continously change in size but appear discretely at a given threshold and are the same size at higher thresholds in an all-or-nother sort of way. I take this to mean that because the monte carlo simulation was performed at a given threshold, the clusters at that threshold size are corrected for mutiple comparisons based on the probability distribution of the chance data (though I don't know the details). Because it is done in this way, it seems I would either have to run several monte carlo simulations, at successively higher minimum thresholds, in order to arrive at the critical cutoff sizes for significance. This is impractical, so I guess my question is, does the way in which the monte carlo simulations are done preclude the possibility of getting the cluster sizes at which they will have a certain CWP value, or is there some way of doing this?

Thanks,
Rob

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Robert P. Levy, B.A.
Research Assistant, Manoach Lab
Massachusetts General Hospital
Charlestown Navy Yard
149 13th St., Room 2611
Charlestown, MA 02129
email: levy@nmr.mgh.harvard.edu
phone: 617-726-1908
fax: 617-726-4078

http://nmr.mgh.harvard.edu/manoachlab