A priori probability is a type of probability that is based on existing knowledge and experience, rather than on data collected from an experiment. It is used to make predictions about an outcome before any data is collected.
How to calculate
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Identify the events of interest.
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Estimate the probability of each event occurring.
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Compare the estimated probabilities to the observed frequency of occurrence.
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Adjust the estimated probabilities if needed.
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Calculate the probability of a particular event occurring, given the estimated probabilities of the events.
Examples
- Estimating the probability of drawing a face card from a deck of playing cards.
- Estimating the probability of rolling a six on a single die.
- Estimating the probability of drawing a black ball from an urn with five black balls and five white balls.
- Estimating the probability of obtaining an even number when rolling two dice.
- Estimating the probability of drawing a jack from a deck of playing cards.