Bayesian probability

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Revision as of 22:02, 19 April 2009 by Vladimir Nesov (talk) (Bayesian moved to Bayesian probability: Bayesian, as used on OB/LW, is an agent implementing Bayesian inference. This article is about Bayesian interpretation of probability.)
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A bayesian is someone who views probability as a level of certainty relating to a potential outcome or idea. This is in contrast to a frequentist who views probability as a representation of how frequently a particular outcome will occur over any number of trials.

An event with a probability of .6 (or 60%) will be viewed by a bayesian as stating "I am 60% confident event X will happen in this next trial", whereas a frequentist would view it as stating "Over 100 trials, we should observe event X approximately 60 times."

The difference is more apparent when discussing ideas. A frequentist will not assign probability to an idea, either it is true or false and it cannot be true 6 times out of 10. A bayesian however views ideas in a different light, the probability of an idea being true is equal to the number of possible worlds where it is true out of the total number of possible worlds.

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