Hi everyone; just want to double check my understanding of leading Edges in fgsea; according to FAQ of original gsea

"For a positive ES (such as the one shown here), the leading edge subset is the set of members that appear in the ranked list prior to the peak score. For a negative ES, it is the set of members that appear subsequent to the peak score."

so what i understand is that for positive NES; the expression values of leading Edges (the ones that drive the enrichment) follow the same direction of the ES ( upregulation) but for negative NES; the expression values of leading Edges are the opposite direction of the negative NES. Is my understanding correct?

Hope to hear some clarifications, thanks

Yes, from a practical perspective, genes in the leading edge of up-regulated pathways (with positive ES) are also up-regulated, and for the down-regulated pathways they are also down-regulated.