# Difference between revisions of "Bayesian probability"

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'''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. | '''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 | + | An [[Wikipedia:Event (probability theory)|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. | 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. | ||

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==See also== | ==See also== | ||

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==Blog posts== | ==Blog posts== | ||

+ | *[http://lesswrong.com/lw/s6/probability_is_subjectively_objective/ Probability is Subjectively Objective] by [[Eliezer Yudkowsky]] | ||

*[http://lesswrong.com/lw/oj/probability_is_in_the_mind/ Probability is in the Mind] by [[Eliezer Yudkowsky]] | *[http://lesswrong.com/lw/oj/probability_is_in_the_mind/ Probability is in the Mind] by [[Eliezer Yudkowsky]] | ||

*[http://lesswrong.com/lw/sg/when_not_to_use_probabilities/ When (Not) To Use Probabilities] by [[Eliezer Yudkowsky]] | *[http://lesswrong.com/lw/sg/when_not_to_use_probabilities/ When (Not) To Use Probabilities] by [[Eliezer Yudkowsky]] |

## Revision as of 20:28, 23 July 2009

**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.

## See also

## 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"