Why so many doubles, though?

[Jellby]

I played a game where I rolled:

2+3
5+1
4+4
1+2
3+3
6+2
4+1
3+4
5+6
4+2
...

What is the probability of this exact sequence? It's astronomical! The game is rigged!

[Vandaley]

I played a game where I rolled:

2+3
5+1
4+4
1+2
3+3
6+2
4+1
3+4
5+6
4+2
...

What is the probability of this exact sequence? It's astronomical! The game is rigged!

Thank you for this.

[Vandaley]

I've been meaning to post this since I don't know when, but dang, this is super freaking frustrating. Whoever wrote this iniquitous dice system for this game, I would like to inform you that it is exceptionally bad. I'm really starting to hate how this game works here. I've had opponents that "roll" 13 to 15 doubles in a single game. Now, I've been playing backgammon for over 20 years and the probability of rolling that many doubles is way way way lesser that in this online implementation. It's not because I lost half the games I played here that I'm writing this, it's because of how I lose them. It's like 4 out of 5 games the dice rolling is noticeably favoring one of the two players. It's only a game, yes, I know, but it gets annoying at some point.

Here is your data that shows you are rolling doubles 16.86% of the time.:

bgam.jpg (134.81 KiB) Viewed 906 times

[dschingis27]

It's like 4 out of 5 games the dice rolling is noticeably favoring one of the two players.

That's a pretty accurate description of the Backgammon game. It is bound to happen by the rules of Backgammon that usually one player is favoured by the dice in a particular game.

My newest theory: I guess many players who end up playing Backgammon online are often used to less good opponents in their real life. Now on BGA they get matched with reasonably good players and they suddenly make the experience that they only win 50% of the games and the outcome of games is mostly determined by luck, what a surprise.

[rab1]

Nonsense I’m afraid- the games are always rigged in favour of the player that has lost the most games recently- Algorithms are shocking. They have to change to random

[ViennaManInCA]

I‘ve heard this sentiment from many players. It is annoying both for and against you. It takes away winning by skill. Last game I had 2 double sixes and 3 double fives against me in a row in the end game. What are the odds? Sorry, but after a couple of years using the platform I‘m out of here. Enough is enough.

Cheers,
Bernhard

[gsantiago]

Je suis très frustré par ces lancés de dés qui me pénalisent systématiquement ces derniers temps !
J'ai commencé à avoir de sérieux doutes sur la loyauté de vos algorithmes. Ne me répondez pas, sauf si vous décidez de m’éjecter, puisque vous semblez maîtriser les algorithmes...

[JBeachy]

I just lost a game where my opponent rolled 8 doubles in a row. 11 of their final 13 turns were doubles, and 13 of their 26 total dice rolls were doubles.

[Romain672]

I just lost a game where my opponent rolled 8 doubles in a row. 11 of their final 13 turns were doubles, and 13 of their 26 total dice rolls were doubles.

Let me check since that claim would be really weird if it was true, here is all his rolls of his game (https://boardgamearena.com/gamereview?table=324587603 ):
ndnnndnnnnnnnddddddddnnddd

13doubles/26, so this was true. it has a probability of (https://docs.google.com/spreadsheets/d/ ... 1846324187 ): 0.009%. 1/11 012.

You find 8 doubles in a row, it has a probability of (8^6) 1/1 679 616.


But a single probability said nothing, so let's go deeper.
Usually when people find some weird events about double happening, they will look for their double, the opponent double, or both number of doubles.

So, let's take back that 1/11 012, I will 'multiply properly' (i will explain at the very bottom what i mean by that) by 3, and find 1/3 671 which I assume would be the probability I would keep for your game.
But not for your profile, since you did 138 games of backgammon, i could go further and 'multiply properly' by 138. And I find 1/27. So congrats, if 27 people like you played backgammon for 138 games and shared in the forum their game with the most amount of double between yourself, the opponent, or both player, you would be the one which would get the most unlikely outcome.

And let's take back the second which was 1/1 679 616.
On your game, there was 26 rolls, so there was 19 (26-8+1) starting of 8 streaks of 8 doubles possible. So let's start by 'multiply properly' by 19: 0.001131%, so 1/88 401. Then multiply properly by 3 because you could take your number of double, opponent number, or both player doubles: 0.00339%, so 1/29 467 which is for me the probability i would keep for that game.
Then for your profile, i can multiply properly by 138: 0.467%, which give 1/214. So if 214 people like you played backgammon for 138 games and shared in the forum the highest number of doubles in a row they got in a single game, you would be the highest.

(and finally about 11 doubles / 13 at the end, it's cherry picking, so I will not analyse that)


My two cents is that it's not likely, so thanks for sharing, but we would need way more testimony like yours to see something weird is happening. Many people just share some thoughs with their game, when in reality, their perception of randomness is wrong and just got slightly unlucky, or just got their one game out of one hundred the most weird.
And thanks for not lieing on your post, it's pretty rare


Finally, since people like saying my maths are wrong (mainly because of langage barrier), I'm open to discussion. But let's said you rolled 5 dices, and got 2 doubles in a row at maximum. It has a probability of 1/36. Then You can have ddnnn or nddnn or nnddn or nnndd for your two doubles in a row, which leave 4 possibilities (5-2+1). So I will multiply properly by 4: "1-(1-1/36)^4" which leave 10.7% chance. You can see that multiply by any number will never make it reach 100% since it multiply the 1-x probability with itself.

Thanks for reading

[DistantBabble]

100% agree.
Too many doubles and the inner wall being built every single game just doesn't have in real life.
Always getting the perfect rolls to fill in that whole inner table blows my mind every time...

but yes, so many doubles. recently won a game because I rolled back to back double 5s. absurd.