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

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

From Textbooks • Nov. 29, 2017

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 order to solve Example 3.30 we had to draw upon the concept of conditional probability from the previous section.

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

Many mundane mistakes in reasoning can be traced to a shaky grasp of the notion of conditional probability.

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