[contravariant]

The absence of any cases is strong evidence against the null hypothesis that the both are independent (assuming the combination isn't just much harder to diagnose), but it isn't strong evidence for it being impossible. Just because something hasn't happened doesn't allow you to distinguish between it being impossible and it being very unlikely (of course the other way around does work, then this is strong evidence that it is possible).

[K0SM0S]

I will yield to your logic, and thanks for taking the time to explain how my approximation was flawed. I really need to brush up my logic skills... I did say "hint" though, which really means it is hypothesis, not strict logic at that point.

Edit: wait, no, I re-read my post and clearly, I did not make the logical fallacy. You're correct, and I did see that, hence using the word "hints at", not "means that". But my wording was bad afterwards ("is" instead of "would be"). : ) so thanks for clarifying.