[FieldTrip] bug in FDR script
Kathrin Müsch
kathrin.muesch at gmail.com
Thu Nov 19 18:46:45 CET 2015
Hi,
I realized that the fdr.m file gives a wrong output for the case that the smallest p values are above the FDR threshold. This means that the smallest p-values might be rejected, whereas lower p-values could pass the test. I have filed it as a bug (#3008).
The current script only declares the p-values below or equal to the threshold as significant, whereas in fact all p-values that are smaller or equal to the largest p-value below or equal to this threshold should be declared significant according to the original paper ("find the largest P value that is below the line [threshold]. All voxels with P values less than or equal to this are declared active.”).
I assume that the following line is incorrect and should be replaced by the one below:
Incorrect: h = (ps<=pi);
Correct: h = ps<=(max(ps(ps<=pi)));
Cheers,
Kathrin
--
Kathrin Müsch, Ph.D.
Department of Psychology
University of Toronto
Toronto, Canada
www.honeylab.org
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