Hello, I have a question about the cluster-correction method in a higher-level FEAT. I am trying to figure out the critical cluster size that was used. I am writing a paper and am trying to address a reviewer concern. In the study, we used FSL FEAT to compare connectivity levels between a group of patients versus controls. In post-stats, for the cluster method, we p< 0.0125 (because we ran 4 separate FEAT analyses for 4 different seeds) and the default of z >2.3. Then we reported the clusters that met the significance after FSL's gaussian random field theory cluster correction approach with these parameters. The reviewer asked us for the cluster-defining threshold (as a p value) and the corrected critical cluster size.
I can not see how get this information from the FSL results report. All I can see is their description of the approach:
“FMRI data processing was carried out using FEAT (FMRI Expert Analysis Tool) Version 5.98, part of FSL (FMRIB’s Software Library, www.fmrib.ox.ac.uk/fsl). Z (Gaussianised T/F) statistic images were thresholded using clusters determined by Z > 2.3 and a (corrected) cluster significance threshold of P=0.0125 [Worsley 2001].”
I can go into the report and see the p value associated with the cluster (it was 0.007-- not sure if that is considered corrected or uncorrected) but I can not see anything about a critical cluster size that was used to determine the clusters meeting criteria.
So here are my questions:
1. Is there a way to find out the critical cluster size?
2. Is the p value that I found by clicking on the cluster in the report document corrected, or uncorrected?
Thanks, Katie
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