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April 24th, 2014 at 2:49:17 AM permalink
Tomorrow in Australia is ANZAC day, part of the tradition on ANZAC day is to play 2UP at the pubs and clubs.
For those that dont know the game, 2UP is a game where 2 or 3 coins are tossed and people bet on either heads or tails, in the case of 2 coins where one of each lands it is thrown again until resolved.
My question is does 2 coins or 3 coins being thrown have a lower variance within resolved outcomes?
Or are they both the same??
Mission146
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April 24th, 2014 at 7:11:37 AM permalink
If I am understanding your question correctly, the per-play Variance would be greater with three coins because every single toss results in a Resolution, whereas, you have a 50% chance of a tie with two coins.
https://wizardofvegas.com/forum/off-topic/gripes/11182-pet-peeves/120/#post815219
AxiomOfChoice
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April 24th, 2014 at 9:41:06 AM permalink
Quote: Stats

Tomorrow in Australia is ANZAC day, part of the tradition on ANZAC day is to play 2UP at the pubs and clubs.
For those that dont know the game, 2UP is a game where 2 or 3 coins are tossed and people bet on either heads or tails, in the case of 2 coins where one of each lands it is thrown again until resolved.
My question is does 2 coins or 3 coins being thrown have a lower variance within resolved outcomes?
Or are they both the same??



They are the same.
Mission146
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April 24th, 2014 at 10:04:25 AM permalink
Oh, only considering resolved outcomes...
https://wizardofvegas.com/forum/off-topic/gripes/11182-pet-peeves/120/#post815219
kubikulann
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April 24th, 2014 at 11:00:06 AM permalink
Consider not the process but the outcomes. Only two cases (heads or tail, win or lose, yes or no, boy or girl... no! scrap that one).
Then consider the probabilities. Every process described gives an equiprobable situation, i.e. 50% either way.

So the games are identical, not only in terms of variance but any other prob. parameter.

Differences are in time / number of throws needed, of course. And maybe in terms of enjoyment or suspense.
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mustangsally
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April 24th, 2014 at 11:19:22 AM permalink
Quote: kubikulann

Differences are in time / number of throws needed, of course. And maybe in terms of enjoyment or suspense.

making 100 bets on each game lowers the probability of a net win for the 2 coin game verses the 3 coin game.
The 2 coin game will have a probability of showing a net loss of about 47.18%
where the chance of a loss with the 3 coin game is about 46.02%

Some can feel that difference

was this not what started probability study over 300 years ago, a small difference like this over some length of play
rolling a pair of 6s in 24 rolls
that was between 49.140388% and 50.553155%

we can see what a larger variance looks like over another smaller one when considering all possible game outcomes, because they are there.
N=100
3 coin game = green

Sally
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kubikulann
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April 24th, 2014 at 11:41:10 AM permalink
Sally,
Do we speak of the same game?
Betting heads or Tail should bring the same "net" result, whether once or a hundred times. So I don't see how this could produce anything other than 50%?

My understanding:
2UP - heads wins if two heads, (resp. tails) and there is a tie if the coins land heads and tails.
3UP - heads wins if there are two or three heads. (resp. tails)
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AxiomOfChoice
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April 24th, 2014 at 12:07:43 PM permalink
Quote: mustangsally

making 100 bets on each game lowers the probability of a net win for the 2 coin game verses the 3 coin game.
The 2 coin game will have a probability of showing a net loss of about 47.18%
where the chance of a loss with the 3 coin game is about 46.02%

Some can feel that difference

was this not what started probability study over 300 years ago, a small difference like this over some length of play
rolling a pair of 6s in 24 rolls
that was between 49.140388% and 50.553155%

we can see what a larger variance looks like over another smaller one when considering all possible game outcomes, because they are there.
N=100
3 coin game = green

Sally



No, I think you are misunderstanding the game as stated. There are no pushes. If it's a tie, they re-flip. Both are 50/50 games; the only difference is the procedure that they use to choose the outcome.
mustangsally
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April 24th, 2014 at 12:17:50 PM permalink
Quote: kubikulann

Sally,
Do we speak of the same game?
Betting heads or Tail should bring the same "net" result, whether once or a hundred times. So I don't see how this could produce anything other than 50%?

yes, the ev = 0 and that can be seen in the chart

Quote: kubikulann

My understanding:
2UP - heads wins if two heads, (resp. tails) and there is a tie if the coins land heads and tails.
3UP - heads wins if there are two or three heads. (resp. tails)

sounds good to me
How about just 2 games played for each.
Let us see the chnace of a net loss

3UP we can lose 2 units with p=.25
even = .50
+2 units = .25

so a 25% chance of a net loss after two games played

The 2UP
net: prob
-2: 6.250000
-1: 25.000000
0: 37.500000
1: 25.000000
2: 6.250000

Looks like a 31.25% chance of a losing session for just 2 games played with Ties included as they are a possible outcome.

Of course the average loss and win will be different too because of variance.

Sally
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mustangsally
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April 24th, 2014 at 12:21:35 PM permalink
Quote: AxiomOfChoice

No, I think you are misunderstanding the game as stated. There are no pushes. If it's a tie, they re-flip. Both are 50/50 games; the only difference is the procedure that they use to choose the outcome.

I see one game can end in a tie.
But if the rules state the game MUST end and it could take 30 years to end the game???

I was just comparing 100 games played including ties and 100 games for the 3UP

So, it would then take more than 100 games for 2UP to have 100 resolved games.

Like the dont pass and pass line bets at Craps
Each player makes 1000 bets but only the pass line player has a probability of 1 of seeing 1000 resolved wagers
Sally
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AxiomOfChoice
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April 24th, 2014 at 12:31:17 PM permalink
Quote: mustangsally

I see one game can end in a tie.



No, it can't. If there is one head and one tail it is not a tie; they re-flip.

Quote:

But if the rules state the game MUST end and it could take 30 years to end the game???



Yup. That is the way that the question was phrased. It's totally reasonable, too -- lots of games work like that. In baseball (not to mention the playoffs of just about every other sport) they play until someone wins.

Quote:

I was just comparing 100 games played including ties and 100 games for the 3UP



Yes, but the question specifically asked not to include ties.

Quote:

So, it would then take more than 100 games for 2UP to have 100 resolved games.



Depends on your definition of "game". Over here, it is being used to mean "resolution".
kubikulann
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April 24th, 2014 at 12:34:30 PM permalink
Quote: Stats

For those that dont know the game, 2UP is a game where 2 or 3 coins are tossed and people bet on either heads or tails, in the case of 2 coins where one of each lands it is thrown again until resolved.

The OP specifically states "thrown again until resolved". A bet never ends in a tie.

And, frankly, the 30 years hypothesis is more than far-fetched. In practice, all games will be resolved in less than two minutes.
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AxiomOfChoice
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April 24th, 2014 at 12:35:39 PM permalink
Quote: kubikulann

The OP specifically states "thrown again until resolved". A bet never ends in a tie.

And, frankly, the 30 years hypothesis is more than far-fetched. In practice, all games will be resolved in less than two minutes.



I don't know; I have to assume that there is a lot of drinking involved here. 2 minutes might be less than the median time to find the coins...
kubikulann
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April 24th, 2014 at 12:38:30 PM permalink
:-) +1
Especially each time they roll off the table...
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Johnzimbo
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April 24th, 2014 at 3:34:47 PM permalink
Any oldtimers here remember when they played this game at Rosie O'Grady's (now MSS) about 25 years ago?
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April 24th, 2014 at 4:39:35 PM permalink
Thanks for the replies.
Ok good to know.
On my way to watch the 11am service and then for a few beers and bets with the diggers!
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