reno
reno
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August 29th, 2019 at 8:06:41 AM permalink
Sometimes when you flip a coin, things happen that might appear unusual, but are actually rather ordinary. For example, you might get 8 heads in a row on 8 consecutive flips.

But at a certain point, the odds become ridiculous. Here's my question: at what point would someone educated in math become suspicious about the integrity of the coin toss? 30 consecutive heads? 50 consecutive heads? 100 consecutive heads?
Gandler
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reno
August 29th, 2019 at 8:36:30 AM permalink
https://youtu.be/XzYLHOX50Bc

Derren Brown did a "trick" some years ago about getting heads 10 times in a row, using multiple cameras filming continuously to prove it's legit.

He later revealed in another video the "trick" was he filmed himself flipping the coin for 9 hours before getting 10 heads in a row. So the trick was just filming nonstop until he eventually got a 10 head streak.

In the initial show it was spun to be some "luck system" where thinking you are lucky makes you lucky or something like that, it's been years since I watched the full show (the coin trick was one part of the show), culminating with making a whole town luckier by installing lucky statues (I think, it's been a while).
unJon
unJon
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August 29th, 2019 at 11:54:39 AM permalink
Quote: reno

Sometimes when you flip a coin, things happen that might appear unusual, but are actually rather ordinary. For example, you might get 8 heads in a row on 8 consecutive flips.

But at a certain point, the odds become ridiculous. Here's my question: at what point would someone educated in math become suspicious about the integrity of the coin toss? 30 consecutive heads? 50 consecutive heads? 100 consecutive heads?



My starting presumption when someone pulls out a coin to flip is that itís not fair.
The race is not always to the swift, nor the battle to the strong; but that is the way to bet.
7craps
7craps
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August 29th, 2019 at 12:18:36 PM permalink
Quote: unJon

My starting presumption when someone pulls out a coin to flip is that itís not fair.

exactly.
I carry a fair looking 'rounded corners' Die to flip a coin.

let the other select which numbers (3 of them) will be Heads.
still have seen 6,7 Heads in a row with this method while watching that the roll is a fair one.
Makes me wonder
winsome johnny (not Win some johnny)
Ace2
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August 29th, 2019 at 12:18:43 PM permalink
Iíd get suspicious at 57 consecutive heads. This is roughly the same probability of someone winning the powerball jackpot twice in a row, which never has happened and never will.
Itís all about making that GTA
OnceDear
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OnceDear
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August 29th, 2019 at 12:19:44 PM permalink
Quote: reno

Sometimes when you flip a coin, things happen that might appear unusual, but are actually rather ordinary. For example, you might get 8 heads in a row on 8 consecutive flips.

But at a certain point, the odds become ridiculous. Here's my question: at what point would someone educated in math become suspicious about the integrity of the coin toss? 30 consecutive heads? 50 consecutive heads? 100 consecutive heads?

Hmmmmm, I'd base my judgement on the totality of my coin flip watching experience.
I.E. I've watched many hours of blackjack spins and a handful of times, the history display has shown a whole long streak of reds or blacks or odds or evens. I'm not for one second inclined to suspect cheating there because it is to be expected that I would see this, over the long time I've spent observing and maybe even playing.
BUT, the total number of times I've spent watching coin toss results is very low. If I see 10 consecutive heads or tails in the next 6 months, that would be exceptional. If I was martingaling those coin tosses and losing, I'd seriously start to suspect mischief after half a dozen losses....
We can judge the mathematical probability based on numbers and simple maths. On judging a wagering situation, we need to account for human nature and potential fraud far more.
If you watch a guy on stage in a black cape take a chainsaw to a lady who just happened to climb in a box, what do you expect? Do you call 911? Nope!
If you encounter a guy with a chainsaw in a dark alley, do you think to yourself 'this will be fun, I'll watch' or do you flee ( or shoot the guy )?
Situation and context matters.

There was a stage magician on tv who showed an experiment. On the street with a small camera crew and sound guy present, he asked young ladies for their engagement rings and then dropped them into the street drain. He then said, 'oh sorry, still, what did you expect?' and he and the camera crewe walked away. The reaction of the 'victims' was priceless. Fortunately for those hysterical ladies, he got their rings back to them later.
Take care out there. Spare a thought for the newly poor who were happy in their world just a few days ago, but whose whole way of life just collapsed..
reno
reno
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August 29th, 2019 at 12:40:29 PM permalink
Quote: OnceDear

...the history display has shown a whole long streak of reds or blacks or odds or evens. I'm not for one second inclined to suspect cheating there because it is to be expected that I would see this, over the long time I've spent observing and maybe even playing.
BUT, the total number of times I've spent watching coin toss results is very low.



I used coin toss as an example, but you could substitute roulette or craps or blackjack or whatever (though obviously the odds of red on a roulette wheel aren't the same as a coin toss because of the green zero(s).)

If I saw 10 consecutive red numbers winning on a roulette wheel, I wouldn't necessarily be suspicious. But 20 reds in a row? 30? 40? At a certain point, you'd have to wonder.

Just wondering what would raise eyebrows among mathematicians.
DRich
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August 29th, 2019 at 1:03:31 PM permalink
At 15 I would be concerned.
Living longer does not always infer +EV
OnceDear
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odiousgambit
August 29th, 2019 at 1:07:34 PM permalink
Quote: reno

Just wondering what would raise eyebrows among mathematicians.

Context: It's all about context. Why am I watching the coin flips? Does the coin flipper have a vested interest?
There are few situations where I'd be inclined to even watch a short sequence of flips? Those times I would be interested would, by definition, be times when I expected mischief.
Guy on stage? Street hustler? Nephew saying hey look what I can do? Carnival game?
I'd get suspicious after 2 flips the same?
Online simulated coin flip at an online casino? I'd expect about 10% bias at the outset and would not trust it at all.

Nope.... No way I'd trust anyone offering a coin flip demonstration.
Take care out there. Spare a thought for the newly poor who were happy in their world just a few days ago, but whose whole way of life just collapsed..
michael99000
michael99000
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August 29th, 2019 at 1:32:41 PM permalink
At 32 heads in a row, I become suspicious

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