The probability of the coin landing on the side initially facing up is slightly higher
because the force of the hand when tossing affects the coin.
The 'number of outcomes' in coin tossing is two: heads or tails. Therefore, the probability is 50% each, making it a 'fair game.' But is this true in reality? Recently, Dutch researchers made headlines by proving the fact that the probability changes depending on which side was facing up when the coin was first tossed, after tossing a coin an astonishing 350,000 times.
The research team, including researchers from the University of Amsterdam in the Netherlands, recently published the results of tossing 46 different coins from around the world 350,757 times on the preprint site 'arXiv.'
The experimental method was simple. Each time the coin was tossed, they recorded which side?heads or tails?was facing up before the toss, which side it landed on, and also filmed the process.
This experiment set the record for the highest number of coin tosses in history. Previously, experiments were conducted on the scale of 20,000 tosses.
The results were unexpected. Contrary to the common belief that the probability of heads or tails is 50% each, the side that was initially facing up had a slightly higher probability of 51% of landing face up. Moreover, depending on the person tossing the coin, this probability rose up to 60%, confirming significant individual variation.
In fact, these experimental results had been predicted before. In 2007, Persi Diaconis, a mathematics professor at Stanford University, along with Susan Holmes, a statistics professor, and Richard Montgomery, a mathematics professor at California State University, Santa Cruz, made similar predictions.
They revealed that due to the force of the hand when tossing the coin, a slight wobble occurs, causing the side initially facing up to stay in the air a bit longer. As a result, the probability of that side landing face up is slightly higher. The University of Amsterdam research team's experimental results confirmed this theory.
A difference of about 1% may seem minor at first glance, but when coin tossing is repeated continuously, the results gradually diverge. For example, the researchers conducted a game where tossing heads earned $2, and tails earned nothing, repeated 1,000 times. Knowing which side was more favorable in advance could yield a profit of $19.
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