Hi,
I am attempting to use phyper to test the significance of two overlapping lists. I keep getting a zero and wondered if that was determining non-significance of my overlap or a p-value too small to calculate?

overlap = 524
lista = 2784
totalpop = 54675
listb = 1296

phyper(overlap, lista, totalpop, listb,lower.tail = FALSE, log.p=F)
[1] 0

If I plug in some different values I get a p-value but since zero is actually lower is the overlap significant, or more likely have I made a mistake in using the function?
phyper(10, 100, 20000, 100,lower.tail = FALSE, log.p=F)
[1] 2.582795e-12


Thanks

Elliott



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