Well, possibly. Let's compute some simple p-values: Suppose that some fraction p of potential speakers are female. Then the probability that all 22 of the spea

Well, possibly. Let's compute some simple p-values: Suppose that some fraction p of potential speakers are female. Then the probability that all 22 of the speakers are male would be (1-p)^22. For p = 0.1, we have a p-value of 0.098, which could reasonably arise by chance. But for p = 0.20, we have a p-value of 0.0074, which is not so likely to arise by chance. So if you assume that at least 20-25% of potential, qualified speakers were female--a reasonable assumption, I think--then this "cluster" does indeed suggest a bias.