law of averages

American  

noun

1. a statistical principle formulated by Jakob Bernoulli to show a more or less predictable ratio between the number of random trials of an event and its occurrences.

2. Informal. the principle that, in the long run, probability as naively conceived will operate and influence any one occurrence.

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law of averages British  

noun

1. (popularly) the expectation that a possible event is bound to occur regularly with a frequency approximating to its probability, as in the (actually false) example Compare law of large numbers

   after five heads in a row the law of averages makes tails the better bet

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law of averages Idioms  

1. The idea that probability will influence all occurrences in the long term, that one will neither win nor lose all of the time. For example, If it rains every day this week, by the law of averages we're bound to get a sunny day soon. This colloquial term is a popular interpretation of a statistical principle, Bernoulli's theorem, formulated in the late 1600s.

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Example Sentences

Perhaps the law of averages means this was bound to happen at some point, but, this season, two players already knew each other from having a mutual friend.

From BBC • Jan. 1, 2026

“It’s been a little bit tougher for me this year. Hopefully the law of averages says it’s going to get a little better.”

From Washington Times • Jun. 1, 2023

Some might attribute the uptick in numbers to the law of averages — a player of Quandre’s caliber was eventually going to stuff the stat sheet, right?

From Seattle Times • Jan. 11, 2023

In the record ninth overtime, the law of averages prevailed and Illinois completed a forward pass to win the game 20-18.

From Los Angeles Times • Oct. 28, 2021

Would the law of averages catch up to him?

From "The Chocolate War" by Robert Cormier