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

Because this is a conditional probability, we restrict the sample space to consider only those outcomes that have a blue marble in the first draw.

From Textbooks • Mar. 27, 2020

Write your answer as a conditional probability statement.

From Textbooks • Sep. 19, 2013

"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 of the card being red-red given that it’s not black-black is VS, but that’s not the situation here.

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