第32页 2.3: Forward probabilities and inverse probabilities

计算后验概率时，其他的可能结果(并没有发生)及其概率与后验概率的计算无关，这个规则就称为 likelihood principle。尽管这条规则简单，但是许多传统的统计方法与之违背。
The details of the other possible outcomes and their probabilities are irrelevant.
All that matters is the probability of the outcome that actually
happened (here, that the ball drawn was black) given the dierent hypotheses.
We need only to know the likelihood, i.e., how the probability of the data
that happened varies with the hypothesis. This simple rule about inference is
known as the likelihood principle.

The likelihood principle: given a generative model for data d given
parameters [;\theta;], [;P(d|\theta);], and having observed a particular outcome
[;d_1;], all inferences and predictions should depend only on the function
 [;P(d_1|\theta);].

In spite of the simplicity of this principle, many classical statistical methods
violate it.

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