[Free]

@Han: I have a master in computer science. Over the years we had at least 4 courses which included different kinds of logic and probability calculations. For these courses I had 12, 14, 15 and 16. These were actually the better scores of my entire studies. Since you can't stand me, I'm sure you won't believe this.

So, while I know what I'm talking about, and while is said like 10 times that I know that in the long run it cancels out, it doesn't cancel out in short games of about 10 boards.

Switching sides and who has more HCP is similar to flipping a coin and guessing what it is. This is also similar to flipping 2 coins at the same time and see if they match (this case I actually got in one of the courses). You have 4 possible results, 2 winning, 2 losing, so yes, you keep having 50-50 win-loss distributions. However, there are 2 factors playing, while flipping 1 coin only has 1 factor. This makes a difference in the short run.
Shooting at myself, but switching seats can even cause the reverse effect: NS having more HCP, but my side having an average of 20...

So again, yes, keeping fixed seats won't solve the winning and losing streaks. The point about being vulnerable and not vulnerable is another factor which cancels out in the long run. But keeping fixed seats WILL make you feel less robbed by BBO if you have a losing streak. Having a better feeling when losing is imo an improvement for BBO.

[Codo]

Frederic,

you have your opinion on this topic. But you are quite alone in the dark.

Of course we all had these sessions IRL , at BBO or with the Gibs where you are dealt one bad hand after the other. And we all dislike these hands, espacially at total point tournements or rubber.

But nobody besides you -at least nobody I know- thinks that this bad fealling gets worse because he had all the bad hands as south and no all the bad hands as west.
You are the only one who cares. All others hate the bad hands and do not care about rotating.

And a major point: I deeply belive that my partner and I should built up a bidding system for hands with 3-9 HCPS, because we "never" have more then this. When I get the statistics after the event, we somehow managed to get 10 HCPS on average, but we never feal like this at the table.

So our experience too has a lot to do with what you feal, but not much with reality.

[Free]

P_Marlowe, on Jun 19 2009, 09:18 AM, said:

Simply put: If you are on the loosing side, the probability that
you will stay on this side is higher and growing over time.
The probability that the score will be +-0 will go too zero, if time goes on, if I remember it correct even with exponenatial speed.

Say person A lost 6 coin flips in a row against a neutral person. Person B lost 10 coin flips in a row against another neutral person. You're telling me that person B has more chance of losing again than person A?

You probably ripped this argument completely out of it's context, for example the doubling up method (or how is it called?). It basically states that you start betting on a coin flip, and if you lose you bet the double amount and play again. So flip 1 you invest 1$, flip 2 2$, flip 3 4$,... This way, every time you win, you win all your investments + 1$. Seems great in theory since you can't lose. Your investments increase exponentially (10 losses in a row means you've invested 1023$ and need to pay 1024 to play again - by 20 you need more than 1000000$!). With unlimited amounts of cash, you'd always win. With limited amounts you see that it can go bad very quickly!

[jdonn]

Free, on Jun 19 2009, 04:07 AM, said:

So again, yes, keeping fixed seats won't solve the winning and losing streaks.

Quote

But keeping fixed seats WILL make you feel less robbed by BBO if you have a losing streak.

How don't you see that the first quote being true (I agree) makes the second quote completely illogical?

[gnasher]

Free, on Jun 19 2009, 10:07 AM, said:

Switching sides and who has more HCP is similar to flipping a coin and guessing what it is.  This is also similar to flipping 2 coins at the same time and see if they match (this case I actually got in one of the courses).  You have 4 possible results, 2 winning, 2 losing, so yes, you keep having 50-50 win-loss distributions.  However, there are 2 factors playing, while flipping 1 coin only has 1 factor.  This makes a difference in the short run.

Are you seriously trying to tell us that there's a higher variance in flipping two unbiased coins and seeing if they land the same way up than in flipping one unbiased coin and seeing if it comes up heads?

Going back to bridge, the question of how which seat you're sitting in is relevant only if it affects what cards you are dealt. If the same, or an equivalent, dealing algorithm is used regardless of which seat you're in, the seat can have no effect in either the long term or the short term. To say that it does makes no more sense than to say that a run of bad cards can be caused by a bird flying past the window.

Quote

But keeping fixed seats WILL make you feel less robbed by BBO if you have a losing streak.

I don't have a masters in anything, but even my meagre understanding of logic and probability is sufficient to make me feel equally robbed regardless of where I was sitting when I was dealt the bad hands.

[Free]

awm, on Jun 18 2009, 08:50 PM, said:

~snip~
I suppose there is some psychological effect (but not a real one).

The vulnerabilities on the other hand are an issue. If you play a tourney where you are NV for more than half the hands, your ability to score total points is substantially reduced. Of course, it does average out (mean is the same) but swapping vulnerability at random CAN increase the variance.

I'll summarize and then leave this topic alone again like I did last year.

1. Yes it's psychological, I said that before. Wheither the seats are fixed or not, my total earnings/losses won't change much. It's not about total points and the money after playing 1000 boards, it's about the FUN when playing TEN boards.
2. The variance CAN indeed increase, that's my whole point. Not only by vulnerability, but also by seating. Sitting NS is flipping a coin, being vulnerable is flipping another coin. NS having more HCP is flipping another... You can remove 2 coins from the equation by fixed seats and normal vulnerability changes.
3. The variance can even decrease by switching positions! But see nr 1.

[655321]

I am reminded of this entertaining thread that contains the following glorious quote:

BebopKid, on Sep 6 2007, 01:48 PM, said:

Since I have over 20 hours of college math, I didn't use the non-math method.

[Free]

655321, on Jun 19 2009, 10:58 AM, said:

I am reminded of this entertaining thread that contains the following glorious quote:

BebopKid, on Sep 6 2007, 01:48 PM, said:

Since I have over 20 hours of college math, I didn't use the non-math method.

It's not about the math...

[Little Kid]

I don't play moneybridge, but I would think that if your seating is random and therefore also the vulnerabilities you are assigned then the variance of potential scores increases (as opposed to roughly identical number of times vul/nv with fixed seats). With the extreme examples being always vul and never vul throughout a session. I don't know how the BBO software functions but if seating truly is random then there would be more variance than with fixed seats.

On the topic of hcps and seats, it probably depends a lot on how BBO is programmed? Say it is designed such that throughout a sessions N, S, E and W all have an average of 10 hcps. Then changing seats randomly should also increase the variance on your average hcp range in the session. If the hands are randomly dealt however it makes no difference whatsoever where you are sitting.

But to be honest, I wouldn't really mind the increased variance of my hands and I doubt the small difference there might be would influence my enjoyment. If i got 4333 4432 10 counts on every hand I would be quite annoyed though.

[IdiotVig]

Free, on Jun 19 2009, 05:00 AM, said:

It's not about the math...

Sorry, but you'd be surprized by my knowledge of non-math.

[IdiotVig]

Free, on Jun 19 2009, 05:00 AM, said:

It's not about the math...

Quasi-seriously, we can run an experiment. We'll get some kind of RNG to simulate coin flips. After some arbitrary number of consecutive flips that come up the same (tails = 6, heads = 10, whatever), I'll take 55-45 that you can't name the next one. Whatever stakes you like, minimum 100 trials.

[Free]

IdiotVig, on Jun 19 2009, 01:40 PM, said:

Free, on Jun 19 2009, 05:00 AM, said:

It's not about the math...

Quasi-seriously, we can run an experiment. We'll get some kind of RNG to simulate coin flips. After some arbitrary number of consecutive flips that come up the same (tails = 6, heads = 10, whatever), I'll take 55-45 that you can't name the next one. Whatever stakes you like, minimum 100 trials.

Go to http://www.random.org/integers/?num=100&mi...at=html&rnd=new

Just too bad there aren't any quick statistics...

1 = I win, 2 = you lose

[gnasher]

Little Kid, on Jun 19 2009, 01:32 PM, said:

On the topic of hcps and seats, it probably depends a lot on how BBO is programmed? Say it is designed such that throughout a sessions N, S, E and W all have an average of 10 hcps. Then changing seats randomly should also increase the variance on your average hcp range in the session. If the hands are randomly dealt however it makes no difference whatsoever where you are sitting.

I think all of this discussion has assumed that BBO deals each hand randomly. Obviously any systemic bias in the dealing process might cause the sort of effect that Free is suggesting.

If BBO did do that, though, what if offered wouldn't be "Bridge", since it would breach Law 6E4, which requires that on each deal the result of dealing (other than hand-dealing) be "wholly random". Also, it would mean that Fred (or one of his employees) is an idiot.

[P_Marlowe]

Free, on Jun 19 2009, 04:41 AM, said:

P_Marlowe, on Jun 19 2009, 09:18 AM, said:

Simply put: If you are on the loosing side, the probability that
you will stay on this side is higher and growing over time.
The probability that the score will be +-0 will go too zero, if time goes on, if I remember it correct even with exponenatial speed.

Say person A lost 6 coin flips in a row against a neutral person. Person B lost 10 coin flips in a row against another neutral person. You're telling me that person B has more chance of losing again than person A?
<snip>

No, but the chance that B will be in the minus after the series stopps
is higher, compared with the chance that A will end up in the minus.

In the end I was talking about "random walk", a series of random steps
and the question where do you will end up after the random walk ends.

So to translate this to the topic:
If you start counting, which side has more HCP in a specific tournemanent,
and you discover at one point in time, that one side got more than av.,
the probability that this will be as well at the end of the tournament is higher
than the probabilitiy that you will catch up and have the same amount of
hands with more HCP your way.
Of course at the start of the tournament it is 50/50 on which side you will
end up.
With kind regards
Marlowe

[helene_t]

Dunno if this is what the thread is about, but:
- I suspect at total points non-duplicate there is a small advantage of being vulnerable as the higher game and slam bonuses are not offset by the higher down trick penalties. Also I would expect it to be an advantage to be dealer (or one's p to be dealer!)
- Therefore it is "unfair" if one player is vulnerable/dealer more often than the other.

In the main room where boards are filtered by not having been played before by any of the four players, I can understand that I can be vulnerable more (or less) than 50% of boards, by accident. Maybe also in robot race where if the seats rather than the hands are cycled to give the human the most HCPs (is that actually what happens?). I would expect money bridge to use the usual regular pattern of vulnerability and dealer, though. It surprises me that (or if?) this is not the case.

[hotShot]

helene_t, on Jun 19 2009, 04:07 PM, said:

...
In the main room where boards are filtered by not having been played before by any of the four players,
....

They are also filtered by vul.
Or to be precise, there are 16 pools of boards for any vul. situation and the next board for your table is picked from the pool that has the required vul.

[awm]

Which direction I sit and how many points I get are independent events.

In other words:

Pr[I have x high card points] = Pr[I have x high card points given I am East]

(for any x)

So which direction I sit will not effect either the expectation or the variance of the number of points I receive. Even in a short event, switching seats does not make a difference. It doesn't make things any more random as far as points are concerned.

Of course, my results on the boards are not solely a function of the cards dealt. It also clearly depends on vulnerability (I get a different score for making or failing in the same contract) and on position (the auction will go differently depending on who is dealer).

[uday]

Quote

I would expect money bridge to use the usual regular pattern of vulnerability and deale

I can't --- people might find it advantageous to bail after a desirable vul/positional hand, before the other guy had his.

In MB, the board # is randomized each deal, also sits S and who sits W

[Free]

uday, on Jun 19 2009, 06:31 PM, said:

Quote

I would expect money bridge to use the usual regular pattern of vulnerability and deale

I can't --- people might find it advantageous to bail after a desirable vul/positional hand, before the other guy had his.

In MB, the board # is randomized each deal, also sits S and who sits W

That's an interesting and valid point you have there.

Questions for Uday:
- would it be possible to obligate people to play per 4 boards instead of 1?
- (out of interest) how are the boards randomized? With a true RNG or with a pseudo RNG?

And a general question: would it be a big loss if the vulnerability in MB would always be the same?

[Lobowolf]

Free, on Jun 19 2009, 12:44 PM, said:

And a general question: would it be a big loss if the vulnerability in MB would always be the same?

Yes.