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title: 51%

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# 51%

This year's Ig Nobel Prize for probability (https://www.chemistryviews.org/2024-ig-nobel-prize-winners/) goes to a coin-flipping study.

For your information, the Ig Nobel awards silly (but interesting) research, and is meant as a parody of the Nobel Prize. This time round, a group collected and studied 350k coin flips to conclude with high probability that there is a ~51% chance for a coin flip to land on the same side from which it started. The full paper (https://arxiv.org/pdf/2310.04153) is rather well-written -- the analysis neatly demonstrates applications of Bayesian models.

## Takeaway
- When we perform a coin flip, we induce a wobble to the coin, which causes the coin to spend more time on the same side.
- There is a physics model that predicts this exact ~51% outcome, and the experiment confirms it with large certainty.
- Application: 51% is bigger than house edge for casino blackjack.
- Application: A coin-flip was used as a tie-break in a Filipino local election (https://www.bbc.com/news/world-asia-22551218)
- There is an easy fix to remove this bias -- simply keep the state of the coin hidden before guessing the outcome.

## Fun facts
- Out of the 350,757 coin flips, 4,230 are done with the SGD 50 cent coin.
- SG founding father Lee Kuan Yew won the 1994 IgNobel Psych prize "for his thirty-year study of the effects of punishing three million citizens of Singapore whenever they spat, chewed gums or fed pigeons." (https://en.wikipedia.org/wiki/List_of_Ig_Nobel_Prize_winners)