# Bayesian probability

From Lesswrongwiki

Revision as of 04:31, 29 September 2009 by PeerInfinity (talk | contribs)

**Bayesian probability** represents a level of certainty relating to a potential outcome or idea. This is in contrast to a frequentist probability that represents the frequency with which a particular outcome will occur over any number of trials.

An event with Bayesian probability of .6 (or 60%) should be interpreted as stating "With confidence 60%, this event contains the true outcome", whereas a frequentist interpretation 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.

## Blog posts

- Probability is Subjectively Objective by Eliezer Yudkowsky
- Probability is in the Mind by Eliezer Yudkowsky
- When (Not) To Use Probabilities by Eliezer Yudkowsky
- All Less Wrong posts tagged "Probability"