A priori probability
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The term a priori probability is used in distinguishing the ways in which values for probabilities can be obtained. In particular, an "a priori probability" is derived purely by deductive reasoning.[1] which has the character of saying that, if there are N mutually exclusive and exhaustive events and if they are equally likely, then the probability of a given event occuring is 1/N. Similarly the probability of one of a given collection of K events is K/N.
One disadvantage of defining probabilities in the above way is that it applies only to finite collections of events.
The term "a priori probability" should be distinguished from the use of prior probabilities in Bayesian inference.
[edit] References
- ^ Mood A.M., Graybill F.A., Boes D.C. (1974) Introduction to the Theory of Statistics (3rd Edition). McGraw-Hill. Section 2.2
