After more than 350,000 systematic coin tosses and recording the results, the research showed that any coin will land on the same side it was tossed from “as much as” 50.8% of the time.
As one of the completely random events, which we ourselves can cause every day, the coin toss has long stood out. The process was believed to be completely fair, unless it was a manipulated coin, i.e. it would produce any result, letters or heads, with a 50% probability. Therefore, coin toss is used to determine who gets the first move in many sports, and in the past, for example, whole football matches, which would normally end in a draw, were decided this way. But taking the fairness of coin tossing for granted, no one has bothered to systematically study the process and see if there are factors that could make it less fair, so that the coin “leans” towards one of the outcomes. Until now.
The heads-tails is not entirely random
A large team of scientists gathered around this idea and conducted interesting research. During the experiment, 48 people tossed coins minted in 46 different countries into the air, to avoid bias related to the design of the coins themselves, and recorded the results. In total, they recorded the results of 350,757 coin flips in this way, and in the obtained results they later received statistical confirmation: coin flips are not perfectly fair.
Namely, during the experiment, the initial state was recorded, i.e. the side of the coin facing up before the toss, and then the state after the coin falls back into the palm. The analysis of such extensive and systematically collected data showed that coins, no matter what they are, will fall on the same side in 50.8% of cases.
The reason for this lies in the physics and the way the coin is thrown, i.e. the precession in its movement during flight. This confirms the hypothesis from 2007, which says that due to such wobble in the air, any coin in flight spends a little more time on average oriented the way it was thrown – which leads to a more frequent end of flight on the same side. The prediction said that coins would drop this way 51% of the time, and the empirical data now almost completely confirms this.
How to get a fair throw?
Coin tossing, this experiment further shows, is perfectly fair when it comes to the final outcome: 50% of the time the coin will land on letters and 50% on heads. But the tendency towards one of the outcomes comes only when its initial state is taken into account, and then we see that the roll loses the perfect randomness of the results.
So how do you ensure a completely fair outcome the next time you need to flip a coin? It is recommended to toss the coin several times or before tossing (and choosing the desired result) not to look at its initial position. Or you can use, for example, a digital coin, which you will “throw” by typing “coin toss”, “flip a coin” or “tossing a coin” into the Google search engine.