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Fair coins tend to land on the side they started (2023)

researchgate.net

151–160 of 193 posts

Re: Fair coins tend to land on the side they started (2023)

#151
Useful. This demonstrates that coin flipping merely amplifies noise in human manipulation.

A classic example in the old PSSC high school physics curriculum was a little catapult-like device which tossed a coin, spinning it a few times in mid-air, and repeatably landing it on the same side. It's a demonstration that Newtonian physics is repeatable.

Re: Fair coins tend to land on the side they started (2023)

#152

I learned a trick with flipping coins from a barber at my grandpas shop when I was probably 6 or 7. Since then I've always been able to flip a coin and determine what the outcome is. It's really just being consistent with the flip and the catch.

If this is done with a quick toss and the coin is flipping rapidly in the air, that's pretty impressive.

I knew someone else who could do this pretty reliably. He said it was a “feel the timing” thing. Best analogy he had was maybe like landing an ice skating triple jump, or a complex dive. It happens too fast to be consciously controlled. Instead the trick is to train the body to get a feel for success and then just let the body do it.

Re: Fair coins tend to land on the side they started (2023)

#153
post #12

Earlier quoted context omitted.

Ah man, please use Bayesian statistics there... Well, the presenter says he doesn't know much about statistics.

The paper does use Bayesian statistics. Presenter is a pure maths PhD.

I don't think I was clear, but I was only talking about the presenter's attempted explanation of the statistics of this problem.

Re: Fair coins tend to land on the side they started (2023)

#154

Hi, I'm the first author of the manuscript, so I thought I could answer some of the questions and clarify some issues (all details are in the manuscript, but who has the time to read it ;) Low RPM tosses: Most of the recordings are on crapy webcams with ~ 30FPS. The coin spin usually much faster than the sensor can record which results in often non-spinning-looking flips. Why did we take the videos in the first place…

The NFL still flips coins professionally. I wonder if they have better-than-webcam footage of each flip. Somewhere out there a bookie might be very interested in any potential bias.

Re: Fair coins tend to land on the side they started (2023)

#156

Hi, I'm the first author of the manuscript, so I thought I could answer some of the questions and clarify some issues (all details are in the manuscript, but who has the time to read it ;) Low RPM tosses: Most of the recordings are on crapy webcams with ~ 30FPS. The coin spin usually much faster than the sensor can record which results in often non-spinning-looking flips. Why did we take the videos in the first place…

The NFL still flips coins professionally. I wonder if they have better-than-webcam footage of each flip. Somewhere out there a bookie might be very interested in any potential bias.

That makes me wonder whether any bookmakers or sports betting arbitration shops have ever internally ran a study like this.

With how much money there is in sports betting, it could potentially be somewhat lucrative, though I wouldn't be surprised if the bias doesn't actually end up mattering that much in practice.

Re: Fair coins tend to land on the side they started (2023)

#157
post #129

My heart goes out the cryptographers. All that code, written over decades, that assumes coin flips are 50:50. So much updating and rewriting to do. Quite a few algorithms that will need a rethink to remain fair.

If your cryptographer's code is based on coin flips, you probably want to find a new cryptographer.

Re: Fair coins tend to land on the side they started (2023)

#158

Hi, I'm the first author of the manuscript, so I thought I could answer some of the questions and clarify some issues (all details are in the manuscript, but who has the time to read it ;) Low RPM tosses: Most of the recordings are on crapy webcams with ~ 30FPS. The coin spin usually much faster than the sensor can record which results in often non-spinning-looking flips. Why did we take the videos in the first place…

The NFL still flips coins professionally. I wonder if they have better-than-webcam footage of each flip. Somewhere out there a bookie might be very interested in any potential bias.

IIRC, past studies have suggested that letting the coin land, rather than catching it, reduces or eliminates the bias.

Re: Fair coins tend to land on the side they started (2023)

#159
Not totally relevant, but I once discovered it's pretty easy to cheat a coin toss, at least with an Australian 20c coin. Flip the coin, catch in your hand, and in the process of transferring it to the back of your other hand, feel which way up it is, and optionally flip it.

With our coins, the head (the Queen's face at the time) is pretty distinct with a large smooth area, compared to the rough feel of the platypus and water.

So if ever you're flipping for anything that matters, make sure the coin lands directly on the ground.

Re: Fair coins tend to land on the side they started (2023)

#160

Easy way to get a fair result from an unfair coin toss: Flip the coin twice in a row, in this case starting with the same side facing up both times, so it's equally unfair for both tosses. If you get heads-heads or tails-tails, discard and start over until you get either heads-tails or tails-heads, which have equal probabilities (so you can say something like HT = "heads" and TH = "tails"). This works even if the coi…

If anyone wants to look up why this might work, it's a Whitening transform [0]. I can't find the name of the algorithm itself being describe in the parent but there's more than just that for accomplishing the same thing. 0: https://en.wikipedia.org/wiki/Whitening_transformation

That's Von Neumann Whitening.
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