So in our example, this p-value is the probability that we would see δ (x) assuming A is not better than B. If δ (x) is huge (let's say A has a very respectable F 1 of .9 and B has a terrible F 1 of only .2 on x), we might be surprised, since that would be extremely unlikely to occur if H 0 were in fact true, and so the p-value would be low (unlikely to have such a large δ if A is in fact not better than B). But if δ (x) is very small, it might be less surprising to us even if H 0 were true and A is not really better than B, and so the p-value would be higher.