If we reject the null, we can’t really conclude that selection matters, because there are other neutral models that predict different distributions of alleles. And if we fail to reject the null, we can’t really conclude that evolution is neutral, because some selection models expect the same frequency distribution.
给定一个统计模型，来判断命题A
A不对 不能推到出 B对（或ㄱA对）
A对，不代表B不对，充分不必要条件
