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argos_72



Joined: Mar 02, 2007

Post 22 Posted: Nov 15, 2020 - 18:36 Reply with quote Back to top

Hello
I know this is recurrent topic and in the past I remember to have seen some post explaining how the Random Number Generator of FUMBBL server/client works, but expecially during the RE-ROLLs I think something unclear little bit too much often happen.

In a real match of Blood Bowl with real dices usually the event "DOUBLE SKULLS" -> reroll -> "DOUBLE SKULLS " you hardly get. Even after two or three matches you will see such event rarely. Not necessary to ask Anastasious Papoulis to understand that you have to roll a pair dices more than 1000 times to have 50% of probability to see an event = (double skulls) followed by (double skulls). During a match of BB in average you run 100 2xblock dices, which make 50 times rolls. Probability to get double skulls followed by double skulls rolling 50 times 2 block dices of blood bowl maybe will happen if you repeat this test 20 times (so run 50 times a couples of blick dices... then repeat another 50 times and so on...).I got this event in two different consecutive FUMBBL matches in the last few days . The same with the "double 1s". Here the event is more likely because it is 1/36 and for sure it is possible to see this during a match. to be "fair" this event should be seen in a match where you hit 70 times the single D6 a couple of times.

Also another very unlikely event is that a couple of block dices rerolled give the exact configuratio after a Re Roll.

Would be intersting to understand more on how the randomized works during the "re roll" event.

Would be interesting to have in the dices statistics also the number of unlikely events happened during the match like these ones i mentioned (so not only the total number of skulls , but the total number of "double skulls" or "double 1's" REROLLED and followed by the same event.

thanks for clarification
MattDakka



Joined: Oct 09, 2007

Post   Posted: Nov 15, 2020 - 18:45 Reply with quote Back to top

Hello!
Info about the RNG here: https://fumbbl.com/help:FFB_RNG

About getting 2 x double skulls often: some time ago I rolled 2 x double skulls in a game, then I rolled them again 1 day later, in another match (on 2/12/2019 and on 3/12/2019).
It can happen, but if you keep track of double skulls with a big sample size you will find that they happen as much as expected.
I use to keep track of them, this is why I know it. Very Happy

I rolled 13 quad skulls in the 813 games sample below:

15/11/2019 (4086 games)
02/12/2019 (4124 games)
03/12/2019 (4127 games)
13/02/2020 (4301 games)
03/03/2020 (4354 games)
04/03/2020 (4357 games)
10/03/2020 (4376 games)
16/03/2020 (4389 games)
01/04/2020 (4447 games)
01/06/2020 (4599 games)
26/08/2020 (4774 games)
10/10/2020 (4865 games)
30/10/2020 (4899 games)

average of 1 quad skull every 62,53 matches.


Last edited by MattDakka on Nov 15, 2020 - 19:03; edited 3 times in total
Uber



Joined: Mar 22, 2004

Post   Posted: Nov 15, 2020 - 18:53 Reply with quote Back to top

argos_72 wrote:
Would be intersting to understand more on how the randomized works during the "re roll" event.


There's nothing special happening during the "re roll" event. The odds are the same on any given roll. You're still 1 in 36 of getting double skull regardless of what the previous roll was.

This flaw in reasoning is known as the Gambler's Fallacy:
https://en.wikipedia.org/wiki/Gambler%27s_fallacy

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Recovering FUMBBL addict.
MattDakka



Joined: Oct 09, 2007

Post   Posted: Nov 15, 2020 - 18:56 Reply with quote Back to top

Often there is confusion between the probability of an event and the distribution of the event in a given sample.
Probability of the single event never changes, the distribution does as the sample size increases.
Just play more games and you will be fine! Keep track of quad skulls yourself, you will see the RNG works well.

About physical dice: you don't see often quad skulls in TT because, I guess, when people pick the dice they manipulate them and that makes less likely to roll again the same results compared to an abstract RNG without physical dice. RNG has better distribution than physical dice, also, physical dice can have small flaws altering slightly the odds of rolling some results, this is why casinos replace them often.
stej



Joined: Jan 05, 2009

Post   Posted: Nov 15, 2020 - 20:08 Reply with quote Back to top

It's 50:50 that you reroll double skulls to double skulls anyway. You either roll them or you dont 😉
Nelphine



Joined: Apr 01, 2011

Post   Posted: Nov 15, 2020 - 20:17 Reply with quote Back to top

Another way of saying it: There are hundreds of matches played per day on the site. We would therefore expect at least one person, almost every day, to get quad skulls in consecutive or close to consecutive matches.

So to look at this and see if there is a problem, you would need to look through all the games being played over, say, a week. Yes you might get them - but SOMEONE is bound to get them. So unless you do check all those other games, then the reasonable assumption is that yes, RNG is working as it should - and today you were unlucky.

(Don't get me wrong, I'd like to actually design a better luck calculator, and then apply it over 100 of my own matches, and see how my luck evens out over time, but while I have the inclination to work out the definitions and algorithms that should be used, I don't have the ability to automate that process, nor do I have the patience to manually check that many games. And even then, do to the inherent inbalance between certain actions - dodging the 5th loner on the same turn when your opponent cannot hope to win, vs your opponent blitzing your blodging sidestepping ball carrier - I can't say that any algorithm look at luck will be particularly accurate.)
argos_72



Joined: Mar 02, 2007

Post   Posted: Nov 15, 2020 - 21:11 Reply with quote Back to top

hello all. Thanks a lot for these answers. In fact my was just a guess. For the Bernouilli trials theorem to judge randomicity of an event you should play a lot of matches. Well what shall I say: as I have experienced already my quad skulls event in two consecutive matches, now I am fine for the next 10's!! Mr. Green

P.S)
Does someone know if there is a possibility to download in excel file (or other forma CVS... tht easy to posto process) the match dices results so I can keep my statistics calculation off line?

Thanks a lot all!
Uber



Joined: Mar 22, 2004

Post   Posted: Nov 15, 2020 - 21:19 Reply with quote Back to top

Have you tried clicking this icon on the match report: Image

https://fumbbl.com/FUMBBL.php?page=match&id=4248820

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Recovering FUMBBL addict.
argos_72



Joined: Mar 02, 2007

Post   Posted: Nov 15, 2020 - 23:23 Reply with quote Back to top

yes i did. but this is the pre-defined stats generation code. Which is good but does not tell me the info I am searching. For instance does not give me the information of how many RR I failed, how many "double 1's" i did during the match... or something like this. I would like to download the full sequence of my dices rolls during the match if possible so I can do my statistics.
thanks in advance.
jdm



Joined: Nov 30, 2011

Post   Posted: Nov 15, 2020 - 23:32 Reply with quote Back to top

Sounds like you want this https://fumbbl.com/help:Fumbbl+API

I wish you luck in your pointless quest

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argos_72



Joined: Mar 02, 2007

Post   Posted: Nov 15, 2020 - 23:36 Reply with quote Back to top

thanks!
pythrr



Joined: Mar 07, 2006

Post   Posted: Nov 15, 2020 - 23:36 Reply with quote Back to top

is borked ConSpiroCy.

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MattDakka



Joined: Oct 09, 2007

Post   Posted: Nov 15, 2020 - 23:37 Reply with quote Back to top

Gathering data is nice, but double 1s don't tell the whole story. It's important to know when the double 1s and skulls happen too. So you should know when the double skulls/1s happened and in which situation.
A single 6 in the right moment (last turn pass for example) is more important than a sequence of 6s for not important blocks/AV breaks.
Stingray



Joined: Nov 16, 2009

Post   Posted: Nov 16, 2020 - 02:00 Reply with quote Back to top

MattDakka wrote:
Hello!
Info about the RNG here: https://fumbbl.com/help:FFB_RNG

About getting 2 x double skulls often: some time ago I rolled 2 x double skulls in a game, then I rolled them again 1 day later, in another match (on 2/12/2019 and on 3/12/2019).
It can happen, but if you keep track of double skulls with a big sample size you will find that they happen as much as expected.
I use to keep track of them, this is why I know it. Very Happy

I rolled 13 quad skulls in the 813 games sample below:

15/11/2019 (4086 games)
02/12/2019 (4124 games)
03/12/2019 (4127 games)
13/02/2020 (4301 games)
03/03/2020 (4354 games)
04/03/2020 (4357 games)
10/03/2020 (4376 games)
16/03/2020 (4389 games)
01/04/2020 (4447 games)
01/06/2020 (4599 games)
26/08/2020 (4774 games)
10/10/2020 (4865 games)
30/10/2020 (4899 games)

average of 1 quad skull every 62,53 matches.


It's official: I'm impressed!! Very Happy
The_Murker



Joined: Jan 30, 2011

Post   Posted: Nov 16, 2020 - 02:15 Reply with quote Back to top

There is no alternate 'Random Number Generator' (RNG) that FUMBBL uses for re-rolls. It is the same RNG every time.

If you are looking for support in saying that you are VERY unlucky to roll Quad-Skulls in two games in a row, I think we would all agree, that WAS unlucky. But additionally, lots of folks with 2000+ games played would remember a run of very bad luck and would say it has happened to them as well.

I remember a LOT of QUAD skulls in my 2000+ matches. When I was newer, SKULL-SKULL re-rolled into SKULL-SKULL meant almost certain defeat, as I was often in a crappy position. Sometimes I roll Quad-Skulls now, but I am winning the game, so I don't automatically lose afterwards. It still hurts my feelings, though.

Quite a few guys begin here and wonder about the RNG when they get defeated, or when they really smash someone else. Some leave, but lots stick around anyway, grumble about the dice, and eventually become much better players.

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