However, this distribution ignores the empirical mean and standard deviation of the gene set statistic, which can be approximated more closely by resampling genes. Therefore, for each sample permutation, the mean and standard deviation from gene resampling are used to restandardize the permutation value. Specifically, the restandardized permutation value is computed as S**=μ++σ+σ*(S*−μ*) where (μ+, σ+) and (μ*, σ*) are the mean and standard deviation of gene set scores obtained from resampling sets of genes or permuting sample labels, respectively [36].
