Science of the coin-toss: Bias in Heads-or-Tails

MrSharkey writes " An interesting article published in Science News puts a new scientific spin on the outcome of the venerable coin-toss. "A new mathematical analysis suggests that coin tossing is inherently biased: A coin is more likely to land on the same face it started out on.""

Comments

Re:Mmm-hmm.

[jcrash]

Yeah, whatever. You were lucky. 51% is the stated bias. in 13 tosses, that would possibly bias it one count and even then it is statistically more likely it wouldn't.

Crap science

[lukewarmfusion]

First - the experiment they used to "prove" this involves creating a mechanical device that will flip a coin for you. After some tweaking, they got it to flip and land consistently with heads up.

Of course you can flip a coin (or any other object) and get it to land the same way every time. All it means is that you've eliminated the random factors of human interaction, air, friction, etc. There's nothing inherently random about a coin - it's the random factor in the action.

I say bollocks

[(void*)]

Is a coin fair or unfair. So you perform the experiment 10000 times. Does one expect it to be the same 5000 times exactly? No! The fractional devation expects to see is sqrt(1/10000) = 1%. One should expect to see an error of 1% about 2/3 of the time.

So they did the experirment and got 51%. This is wholly compatible with the notion that the coin is random.

And by the way, ONE trial of 10000 does not prove anything. Show me 51% for ALL trials of 10000 and then lets' talk.

Don't know if that actually works though....

[carlmenezes]

Considering a football game and the grass/turf on the ground, the coin doesn't really get much of a chance to add much randomness due to the amount of energy absorbed - in fact, usually, it falls and lies there - hardly any bounce back. A fairer way would be to have the coin fall on a glass plate so it bounces back more, thereby inserting much more randomness into the toss.

While we're still on the subject, what about using a roulette wheel to decide? Pick red or black and let the ball decide. You can have a nice transparent glass ball (so that you can see that there's no metal inside it to bias it in any way) hitting a metal roulette wheel and glass and metal collisions have among the highest bounce co-efficients.

Re:Tax dollars at work, one coin at a time

[Short Circuit]

Actually, I see this as very important.

Everyone I personally know assumes that coin tosses is a fair, random decision. And that's a fairly fundamental assumption.

This shows that you can assume some things, and you can't assume others. And the list of things you can and can't assume is always changing.

And, just to make your head explode, I'll point out that that means that, over the long term, you can't assume anything.

Think of this research as a sort of lesson in appropriate behavior

Re:Comments from someone who's been studying this

[gowen]

He has obviously seen a magician to the same trick I do. Of course I wont reveal the secret, but I can tell you this: he's wrong.

Or, alternatively, he's seen a Magician do a different trick than yours, and he's right.

Re:Tax dollars at work, one coin at a time

[chef_raekwon]

that coin tosses is a fair, random decision

if the person who calls the toss never sees the face of the coin upon the toss, and doesn't call it until its in the air, is it not still random, and fair?

Start on the side?

[Jtheletter]

So what happens if I perform a coin toss starting with the coin perpendicular to the ground? This should eliminate the bias.
Of course one could also just flip a coin to see which side to start up before performing a coin toss (begin infinite loop regression)....

Re:Tax dollars at work, one coin at a time

[phliar]

We've got a deficit over a half-trillion and things like this are getting funded. Riiiiight.

So we need to stop spending money on everything until the deficit is 0? Equivalently, if you've got a mortgage on your house, then you need to stop spending money on all non-essentials like eating out, owning a car, having more than seven sets of clothes (laundry once a week), computers, eating dessert, ...

Thousands of children die every day, yet things like faster semiconductors are getting funded. Riiiiight.

Re:Tax dollars at work, one coin at a time

[JahToasted]

You're right, of course. I think the difference really is that Bill Clinton actually attended the funerals of those who were killed in action. Bush not only doesn't attend, he doesn't even allow the funerals to be mentioned by the media. Oh, and he also cuts the benefits to any soldier that does survive. A true patriot.