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

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

Independent events are defined as a situation where the conditional probability is simply the probability of the event of interest.

From Textbooks • Nov. 29, 2017

Either C would be pardoned or himself, so by all the laws of conditional probability, his chances of survival had gone up from 1/3 to 1/2.

From Scientific American • Apr. 15, 2011

However, if it’s known somehow that the person chosen is over six feet four inches tall, then the conditional probability that he or she also weighs more than 250 pounds is considerably higher.

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