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## Winning streaks in baseball

Filed in Encyclopedia ,Ideas ,R
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HOW RARE ARE STREAKS?

The New York Mets recently won 11 games in a row, which got a lot of attention.

How likely is it that a given baseball team will win 11 games in a row by chance, if its probability of winning a single game is 50%?

The plot below shows that if a baseball team plays 100 seasons of 162 games, they’ll have an streak of 11 wins in a row about 7 to 8 times a century (about every 13 years on average). If they’re a really good team that wins 60% of the time in the long run, they’ll have an 11 game winning streak 55 times per century (about every 2 years).

Streaks aren’t weird, they’re expected. The graph up top shows that for a team that wins 50% of the time, the most likely outcome is that they’ll have a six game winning streak in a typical 162 game season. There’s an 8% chance their longest streak in a season will be 10 wins or more.

For the gifted team that wins 60% of the time, an eight game winning streak is the most likely outcome in a season, and there’s a 32% chance they’ll have a streak of 10 wins or more.

Fans of R and ggplot2 can reproduce the plots with the code below.