Hi, all,
I have some questions about performing the FDR correction in Qdec.
I ran recon-all on all my subjects, then ran the surface group analysis following the Qdec tutorial. There are 3 factors in the qdec.table.dat file: age, gender and diagnosis. In the Design tab of Qdec, I selected the discrete factor 'diagnosis' for analysis. When the analysis was done, there is a description "Does the average thickness differ between Diseased and Normal?" in the Display tab. I think this should be the uncorrected map. Then I tried to run the FDR correction for multiple comparisons. I set the rate to be 0.05 and 0.01 respectively. However, I found no difference between the results using different rates. In the Terminal, the information are also the same:
"MRISfdr2vwth(): np = 163842, nv = 163842
Found 107008 of 163842 vertices above FDR threshold (of 1.48619)"
I wonder whether I did the analysis correctly. Are such results possible or reasonable?
Thank you in advance.
Best,
Xiaojing
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