conditional probability

American  

noun

1. Statistics, Mathematics. the probability that an event will occur under the condition that another event occurs first: equal to the probability that both will occur divided by the probability that the first will occur.

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conditional probability British  

noun

1. statistics the probability of one event, A, occurring given that another, B, is already known to have occurred: written P ( A|B ) and equal to P ( A and B )| P ( B )

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Etymology

Origin of conditional probability

First recorded in 1960–65

Example Sentences

This is a conditional probability, so consider only probabilities in the row labeled "Caught."

From Textbooks • Mar. 27, 2020

The probability of picking the three of diamonds is called a conditional probability because it is conditioned on what was picked first.

From Textbooks • Nov. 29, 2017

In short, conditional probability is the chance that something will happen given that some other event has already happened.

From Textbooks • Nov. 29, 2017

"Paulos shows a strange lack of understanding of basic conditional probability," wrote one reader, "and as a result his article is nonsense."

From Scientific American • Apr. 15, 2011

The conditional probability that someone speaks English, given that he or she is an American citizen, on the other hand, is probably about 19Ao or .95.

From "Innumeracy: Mathematical Illiteracy and Its Consequences" by John Allen Paulos