## Friday, July 12, 2024

### News You Can Use: Coin Flips Are Not A 50/50 Proposition

Got a smart-ass twelve-year-old you want to take down a peg or two while making a bit of money as you do so? Read on.

From My Modern Met, November 26, 2023:

Scientists Find That Coin Tosses Are Not 50/50 and Determine What Can Give You an Advantage

Coin tossing is generally regarded as a fair and practical way to make a decision between two parties or options. After all, it gives everyone a 50/50 chance to win, right? Well, scientists have determined that the numbers are not so evenly split. Moreover, the balance tends to skew toward one side–giving one of the participants a slight advantage.

Looking at it with statistical eyes, a coin toss begins with the two sides of a coin before a random element is introduced. That is, flipping the coin and catching it—after all, one does not have control about how many times it will spin before falling. But as a team led by American mathematician Persi Diaconis has found, for all the randomness of the flipping, coin tossers may introduce a little wobble. This in turn gives the original side that was facing up more chance of coming out victorious—but just by a little bit.

In a study currently in preprint, a group of scientists set out to test Diaconis' findings and prove that coins land on the same side they were tossed from around 51 percent of the time. “According to the [Diaconis] model, precession causes the coin to spend more time in the air with the initial side facing up,” they write. “Consequently, the coin has a higher chance of landing on the same side as it started (i.e., ‘same-side bias’).”

The team performing the latter study collected 350,757 coin flips, carried out by 48 people using 46 different currencies. In the end, there turned out to be a 50.8 percent chance of the coin showing up the same side it was tossed from. However, some of the tossers had a strong same-side bias while others didn't having any at all, showing that many tosses may come down to whoever is flipping the coin....

....MUCH MORE

I thought we already knew this. A June 2023 post starring the same research team:

Think a coin toss has a 50-50 chance? Think again.

Coming up, how to cheat ten-year-olds at Monopoly without the the drudgery of being the banker.
(using the old dice tricks, the whip shot and the drop shot.)