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Comment by keepshoutingsir | Hacker News Reader

Tl;dr: There’s no particular bias to heads or tails, but a coin will land the same way it was when it was tossed 51% of the time.

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The article is more interesting than just the finding, to those who want to delve deeper. It’s a short biography of Persi Diaconis, an accomplished mathematician with no high school diploma who didn’t start studying mathematics until he was 24.

Really, really fascinating life and experience.

I remembered the result that showed a coin toss was biased that way, but I didn't know that the degree of bias hadn't been nailed down. I guess it makes sense that it varies from person to person. Now I'm interested in an anthropological study of how different people toss coins...

I think it's more random for me because I flip coins onto the floor, not onto my hand, or spin them on the table and see how they land when they stop spinning.

I'm probably being dense but what do you mean by "the same way it was when it was tossed 51% of the time"?

When you flip a coin, it is either heads side up or tails side up as it rests on your thumb. This initial position may slightly affect how it ultimately lands.

Pretty sure it’s because the heads is heavier.

I thought it was common knowledge that heads are heavier than tails. My head certainly is.

HN is way too harsh on jokes, even when they’re really good - like this one.

I think good jokes can get appreciation here, but we try pretty hard to avoid the reddit-style puns and joke chains that distract from the discussion. They're entertaining sometimes... on reddit.

There are plenty of other sites you can go to if you want to read chains of joke comments.

Some folks have big heads, others big tails.

It’s not, it’s because when flipped the number of flips the coin does in the air is not entirely random.

Not only is this (somewhat obviously given the discovered bias) wrong, it’s physically impossible to bias a coin flip by weighting one side. Weighting a coin will change its center of gravity but to bias a flip you would need to impart angular momentum while it is in the air; at any constant rate of spin (again somewhat obviously once pointed out) each side will spend 50% of its time "up" and 50% "down".

https://www.tandfonline.com/doi/abs/10.1198/000313002605

Why does toast land butter side down so often?

If you flip toast rather than drop it, it doesn’t. Also, if you drop it it doesn’t really land “butter side down” but “top side down”. Just butter the bottom of your toast to solve the problem!

https://en.m.wikipedia.org/wiki/Buttered_toast_phenomenon

There's a huge assumption in this assertion: that you catch the coin.

If you let it bounce on a table, it's much more likely to land heavy-side down. Just imagine a very thick coin one side lead the other side balsa wood. That would land lead-side down much more than 50/50 if allowed to bounce on the table.

Do we know the reasoning behind the bias?

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