8 ms·

I've been running a virtual dice roller site for pen & paper roleplayers for about ten years. I get these kinds of emails all the time. "Your RNG is faulty, I j

by Udo 13y ago

I've been running a virtual dice roller site for pen & paper roleplayers for about ten years. I get these kinds of emails all the time. "Your RNG is faulty, I just rolled three 20s in a row!" and stuff like that. It's probably not fixable psychologically, we're just seeing patterns everywhere. This also happens with physical dice by the way. If a player rolled two or more abysmal results in a row it's common to say "hey, you should really swap out these dice".

sturmeh 13y ago
There's more rigging involved with people who can't throw dice properly than there is with the seed of a RNG on a server miles away with you. :P
polymatter 13y ago
I've toyed with the idea of not using a fair RNG for games for this reason. People expect die rolls to converge to the average distribution much much faster than they actually do. So perhaps you can make a RNG program that does exactly that and does what the user expects, even if mathematically ridiculous. For example, if 20 is rolled then the probability of 20 being rolled again is halved (so it has a 1/40 chance) while the probability of its inverse is doubled (so probability of 1 is 1/10). This dramatically reduces the chance of the three 20s in a row scenario and would very quickly regress to the mean, just like people expect. Added flair for affecting the probabilties of all possible values subtly (so that after rolling a 20, a 2 becomes more likely and a 19 less likely). I'm sure I can't be the only person to think of this.
- dllthomas 13y ago
  I don't like the notion of reinforcing bad intuitions.
  - a-priori 13y ago
    People are born with bad intuitions about how randomness works -- it's not learned. For whatever reason, our brains are wired to make uniformity feel random and randomness feel ordered. It's why we see stars in the sky, which are more or less distributed randomly in the star field, yet they don't appear random: they appear to form constellations. It's basically impossible to correct this bad intuition. People educated in the statistics and mathematics of random numbers have to consciously learn what real randomness looks like and override their intuition. But try as you might, the night sky will still form constellations. And dice rolls will still, frustratingly and confusingly, fall into streaks more often than you'd expect.
    - dllthomas 13y ago
      There are a lot of systems in the brain. It's theoretically possible that one of them will be untrainably spitting out the same flawed predictions, but we can certainly learn how to respond appropriately to those sensations.
- fhars 13y ago
  http://en.wikipedia.org/wiki/Sobol_sequence http://en.wikipedia.org/wiki/Sobol_sequence
- merloen 13y ago
  iTunes did that at one time because people complained about the shuffle algorithm for similar reasons.
  - spuz 13y ago
    Shuffling is different from selecting at random. I had an MP3 player that would use random selection instead of shuffling all tracks and it would annoy the hell out of me to hear the same songs twice in a row. I don't know if this is what iTunes used to do but if so then those people were right to complain.
    - ygra 13y ago
      iTunes used a shuffle that always resulted in the same order as long as there was the same number of songs on the device. (Or perhaps just shuffling with a tiny PRNG that used the number of songs as seed.)
    - masklinn 13y ago
      > I don't know if this is what iTunes used to do It is. iTunes would play a song, and randomly select the next one (it would do random play, rather than shuffle). Nowadays it generates a shuffled playlist and goes along, and people whine because it doesn't reshuffle automatically (you have to disable and enable shuffle to reshuffle). An other option is to use random sampling, and to re-sample after you're done with the current set (possibly excluding any song of the previous sample)
- fvirexi 13y ago
  Can't this be partially solved by just throwing multiple dices? E.g two 6-sided dices would then have a higher chance of 7 than 12.
  - netcan 13y ago
    IMO the problem can be best explained with a classroom experiment, almost like a magic trick. It is a built in human intuition which is at odds with the reality of randomness. Split your class into 2. Give half A the players dice and a piece of paper. Give other half B just a piece of paper. Half B plays with imaginary dice, Half A with real dice. Everyone records 20 games of a piece of paper. You hand in the papers and the demonstrator (or maybe a new one that hasn't been in the class, for extra theatrics) looks at the papers. He will accurately place them into separate piles. The trick is that fake randomness and real randomness are different enough that they are distinguishable with a high level of accuracy. Real dice will roll the same number in a row far more often than fake dice. The more games you play, the more accurately they can be distinguished. You can look at the formulas to figure out the odds of rolling the same number 4 times in 100 rolls, but it doesn't drive home the message that your intuition is broken until you see intuition being beaten consistently and reliably by a better tool. It's fun too.
  - nmc 13y ago
    Last year I wrote a short Python script to easily visualize that kind of effect: https://github.com/ncanceill/alea_jacta_lib https://github.com/ncanceill/alea_jacta_lib
- Udo 13y ago
  You're right that would probably lead to better user satisfaction, but I'm not going to implement something like this. I refer you to the answer I've given herokusaki below. Basically, the site is not about straight-up die rolling. It supports a myriad of different rule systems. On top of that, it doesn't keep track of users, so it's not possible to tinker with results based on user state. I have no real intention of changing that either ;)
- tfgg 13y ago
  I've thought about the same for Settlers of Catan, which I think is too random if you use dice, disrupting people's ability to do more than basic strategy. I know there exist "dice" packs of cards, which contain the correct distribution of rolls. If you shuffle a few of those together, you'll probably get a nicer game.
  - cpwright 13y ago
    One of the nice features of the Settler of Catan assistant for the iPhone is that it will roll the dice for you, and it keeps a chart of the results. Thus one has data to back up the complaint that "Your 3 is out producing my 6!"
  - ygra 13y ago
    That sounds like a nice idea, actually. I hate those rounds where 11 or 2 occur more often than 6 or 8. I know it can happen, but it can make the game rather annoying at times.
    - taeric 13y ago
      I actually think that makes the games more fun. Especially so when you have a larger game so that there are people on those tiles. For me, it makes the game feel less "solvable" by basic analysis. Sure, statistically certain observations will hold. For the game you are in, though, you have to be ready to adjust your strategy based on what has happened. (Clearly not in anticipation of future rolls, but more based on the resources you have managed to get, not the ones you wanted.)
      - ygra 13y ago
        Admittedly, we already tend to take the number planning a bit out of the game by initially turning them on the other side and you can only reveal the numbers to hexes you have built at (for the inital round of placing settlements/streets they are revealed after everyone has placed both). Makes for a nice variant where exploration holds surprises, or you can expand to hexes that are already known.
- Fizzer 13y ago
  "Civilization Revolution" does this. Say the player loses a 75% roll, then attempts another identical 75% roll. The game will actually give you better odds for the second roll. I think it's silly -- the game basically lies to you about your odds on the second attempt. Sid Meier talked about it at length in this video: http://www.youtube.com/watch?v=bY7aRJE-oOY http://www.youtube.com/watch?v=bY7aRJE-oOY. It starts around 18:25.
  - arjie 13y ago
    It may be deceitful, but it makes for a better game. Seeing your five hit attack miss five times at 5% miss chance per attack will induce true frustration. Battle for Wesnoth doesn't care. It will be honest, and you will scream in anger.
    - gabemart 13y ago
      > Seeing your five hit attack miss five times at 5% miss > chance per attack will induce true frustration. I was curious, so I worked out the chances of this happening. For a given five hit attack the chance is 0.00003125%, or 1 in 3.2 million. So yes, I imagine it is very frustrating, but it happens incredibly rarely.
  - oftenwrong 13y ago
    you can link to specific times on youtube http://www.youtube.com/watch?v=bY7aRJE-oOY&t=18m25s http://www.youtube.com/watch?v=bY7aRJE-oOY&t=18m25s
- 3JPLW 13y ago
  I've had to do this when training research monkeys in a former life, particularly when there is only one or two parameters being varied. They would learn the 'patterns' far too quickly. After seven heads in a row, they'd stop paying attention and always choose heads for some time afterwards. The solution we settled on was block randomization. But that's probably not what you'd want for a human game as they could potentially figure out the end of each block (and what value remains). But it worked wonderfully for us.
ygra 13y ago
Some people solve this by throwing hardware (and dice!) at it: http://gamesbyemail.com/News/DiceOMatic http://gamesbyemail.com/News/DiceOMatic :-)
herokusaki 13y ago
Fascinating. I wonder if visualizing the dice roll could help. If you don't have ethical objections to it you could also A/B test biased dice (say, biased away from 1 and 20) for complaints (give a different contact email address to players who get biased dice) or instead show the players the distribution of the last 100 rolls.
- Udo 13y ago
  That's not really possible for a lot of reasons. First, the roller is absolutely anonymous. There are basically three major functions the site performs: just rolling some dice according to user input, an API taking HTTP requests answering in JSON, and a chat room feature that has a dice roller bot. It's not possible to identify individual players except maybe in the chat rooms (though they're not really authenticated there either). I do sometimes get requests to look into chat logs of a particular room over allegations that one player somehow tampered with the results. This happens about once a month. Invariably, the accused user isn't even that lucky, they almost always have bog standard average results. It's just that the other players think this person is unreasonably lucky and they keep this belief up even after I tell them about the data (which they could have calculated themselves by looking at their own chat logs). Second, the core value proposition of the site is its ability to render roleplaying dice codes directly. That means you don't select your dice from a drop down - you enter the code. A simple example would be "3d6+5" for damage or something, but there are lots of different codes for different rules - some of them quite convoluted. It's not feasible to tinker with them in any meaningful way because players use the site in so many different ways.
baby 13y ago
Throwing dices in real life is even less random than a "truly" random function.
nmc 13y ago
You are referring to the common mistake of confusing randomness and uniformity. Your players are thinking: "Dice rolls are equiprobable, so I should roll evenly-distributed results." That only starts being true after a great number of rolls. Random distributions will be uneven and present clumps, strands and voids. For the same reason, during WWII, British intelligence thought that the Germans were bombing specific targets in London, while they were just dropping bombs at random. Source recently posted on HN: http://www.wired.com/wiredscience/2012/12/what-does-randomness-look-like/ http://www.wired.com/wiredscience/2012/12/what-does-randomne...
- Udo 13y ago
  If you knew how many times I launched into that randomness vs uniformity lecture myself ;) My point was that it's not possible to convince certain people with logic. They see random numbers and something happens to their brains, maybe it's religion. They'll always see oracles or at the very least shady manipulators behind random data.
- pixl97 13y ago
  https://en.wikipedia.org/wiki/Law_of_large_numbers https://en.wikipedia.org/wiki/Law_of_large_numbers
pessimizer 13y ago
https://en.wikipedia.org/wiki/Representativeness_heuristic https://en.wikipedia.org/wiki/Representativeness_heuristic
raverbashing 13y ago
It should be fun to calculate the chance a RNG is biased based on a die rolling 20 3 times in a roll Similar to that question about biased coins and throwing 10 heads in sequence it was discussed some time ago here.
walshemj 13y ago
It happens at our recent dnd game our mage roiled all 1's on a magic missile 6d4 all 1's
emhart 13y ago
Re: Physical dice. I've gamed a lot over the years, and I don't believe I played with anyone anyone for whom swapping out dice had anything to do with actually effecting randomness/probability, but rather was just a fun way to wish for better luck. And, even then, that move "toward" luck or "away" from bad luck was always tongue-in-cheek. Yet...we still swapped the dice. :)
edraferi 13y ago
Clearly, there is something supernatural afoot: http://www.penny-arcade.com/comic/2014/02/05 http://www.penny-arcade.com/comic/2014/02/05

by Udo 13y ago

sturmeh 13y ago

There's more rigging involved with people who can't throw dice properly than there is with the seed of a RNG on a server miles away with you. :P

polymatter 13y ago

I've toyed with the idea of not using a fair RNG for games for this reason. People expect die rolls to converge to the average distribution much much faster than they actually do. So perhaps you can make a RNG program that does exactly that and does what the user expects, even if mathematically ridiculous. For example, if 20 is rolled then the probability of 20 being rolled again is halved (so it has a 1/40 chance) while the probability of its inverse is doubled (so probability of 1 is 1/10). This dramatically reduces the chance of the three 20s in a row scenario and would very quickly regress to the mean, just like people expect. Added flair for affecting the probabilties of all possible values subtly (so that after rolling a 20, a 2 becomes more likely and a 19 less likely). I'm sure I can't be the only person to think of this.

dllthomas 13y ago
I don't like the notion of reinforcing bad intuitions.
- a-priori 13y ago
  People are born with bad intuitions about how randomness works -- it's not learned. For whatever reason, our brains are wired to make uniformity feel random and randomness feel ordered. It's why we see stars in the sky, which are more or less distributed randomly in the star field, yet they don't appear random: they appear to form constellations. It's basically impossible to correct this bad intuition. People educated in the statistics and mathematics of random numbers have to consciously learn what real randomness looks like and override their intuition. But try as you might, the night sky will still form constellations. And dice rolls will still, frustratingly and confusingly, fall into streaks more often than you'd expect.
  - dllthomas 13y ago
    There are a lot of systems in the brain. It's theoretically possible that one of them will be untrainably spitting out the same flawed predictions, but we can certainly learn how to respond appropriately to those sensations.
fhars 13y ago
http://en.wikipedia.org/wiki/Sobol_sequence http://en.wikipedia.org/wiki/Sobol_sequence
merloen 13y ago
iTunes did that at one time because people complained about the shuffle algorithm for similar reasons.
- spuz 13y ago
  Shuffling is different from selecting at random. I had an MP3 player that would use random selection instead of shuffling all tracks and it would annoy the hell out of me to hear the same songs twice in a row. I don't know if this is what iTunes used to do but if so then those people were right to complain.
  - ygra 13y ago
    iTunes used a shuffle that always resulted in the same order as long as there was the same number of songs on the device. (Or perhaps just shuffling with a tiny PRNG that used the number of songs as seed.)
  - masklinn 13y ago
    > I don't know if this is what iTunes used to do It is. iTunes would play a song, and randomly select the next one (it would do random play, rather than shuffle). Nowadays it generates a shuffled playlist and goes along, and people whine because it doesn't reshuffle automatically (you have to disable and enable shuffle to reshuffle). An other option is to use random sampling, and to re-sample after you're done with the current set (possibly excluding any song of the previous sample)
fvirexi 13y ago
Can't this be partially solved by just throwing multiple dices? E.g two 6-sided dices would then have a higher chance of 7 than 12.
- netcan 13y ago
  IMO the problem can be best explained with a classroom experiment, almost like a magic trick. It is a built in human intuition which is at odds with the reality of randomness. Split your class into 2. Give half A the players dice and a piece of paper. Give other half B just a piece of paper. Half B plays with imaginary dice, Half A with real dice. Everyone records 20 games of a piece of paper. You hand in the papers and the demonstrator (or maybe a new one that hasn't been in the class, for extra theatrics) looks at the papers. He will accurately place them into separate piles. The trick is that fake randomness and real randomness are different enough that they are distinguishable with a high level of accuracy. Real dice will roll the same number in a row far more often than fake dice. The more games you play, the more accurately they can be distinguished. You can look at the formulas to figure out the odds of rolling the same number 4 times in 100 rolls, but it doesn't drive home the message that your intuition is broken until you see intuition being beaten consistently and reliably by a better tool. It's fun too.
- nmc 13y ago
  Last year I wrote a short Python script to easily visualize that kind of effect: https://github.com/ncanceill/alea_jacta_lib https://github.com/ncanceill/alea_jacta_lib
Udo 13y ago
You're right that would probably lead to better user satisfaction, but I'm not going to implement something like this. I refer you to the answer I've given herokusaki below. Basically, the site is not about straight-up die rolling. It supports a myriad of different rule systems. On top of that, it doesn't keep track of users, so it's not possible to tinker with results based on user state. I have no real intention of changing that either ;)
tfgg 13y ago
I've thought about the same for Settlers of Catan, which I think is too random if you use dice, disrupting people's ability to do more than basic strategy. I know there exist "dice" packs of cards, which contain the correct distribution of rolls. If you shuffle a few of those together, you'll probably get a nicer game.
- cpwright 13y ago
  One of the nice features of the Settler of Catan assistant for the iPhone is that it will roll the dice for you, and it keeps a chart of the results. Thus one has data to back up the complaint that "Your 3 is out producing my 6!"
- ygra 13y ago
  That sounds like a nice idea, actually. I hate those rounds where 11 or 2 occur more often than 6 or 8. I know it can happen, but it can make the game rather annoying at times.
  - taeric 13y ago
    I actually think that makes the games more fun. Especially so when you have a larger game so that there are people on those tiles. For me, it makes the game feel less "solvable" by basic analysis. Sure, statistically certain observations will hold. For the game you are in, though, you have to be ready to adjust your strategy based on what has happened. (Clearly not in anticipation of future rolls, but more based on the resources you have managed to get, not the ones you wanted.)
    - ygra 13y ago
      Admittedly, we already tend to take the number planning a bit out of the game by initially turning them on the other side and you can only reveal the numbers to hexes you have built at (for the inital round of placing settlements/streets they are revealed after everyone has placed both). Makes for a nice variant where exploration holds surprises, or you can expand to hexes that are already known.
Fizzer 13y ago
"Civilization Revolution" does this. Say the player loses a 75% roll, then attempts another identical 75% roll. The game will actually give you better odds for the second roll. I think it's silly -- the game basically lies to you about your odds on the second attempt. Sid Meier talked about it at length in this video: http://www.youtube.com/watch?v=bY7aRJE-oOY http://www.youtube.com/watch?v=bY7aRJE-oOY. It starts around 18:25.
- arjie 13y ago
  It may be deceitful, but it makes for a better game. Seeing your five hit attack miss five times at 5% miss chance per attack will induce true frustration. Battle for Wesnoth doesn't care. It will be honest, and you will scream in anger.
  - gabemart 13y ago
    > Seeing your five hit attack miss five times at 5% miss > chance per attack will induce true frustration. I was curious, so I worked out the chances of this happening. For a given five hit attack the chance is 0.00003125%, or 1 in 3.2 million. So yes, I imagine it is very frustrating, but it happens incredibly rarely.
- oftenwrong 13y ago
  you can link to specific times on youtube http://www.youtube.com/watch?v=bY7aRJE-oOY&t=18m25s http://www.youtube.com/watch?v=bY7aRJE-oOY&t=18m25s
3JPLW 13y ago
I've had to do this when training research monkeys in a former life, particularly when there is only one or two parameters being varied. They would learn the 'patterns' far too quickly. After seven heads in a row, they'd stop paying attention and always choose heads for some time afterwards. The solution we settled on was block randomization. But that's probably not what you'd want for a human game as they could potentially figure out the end of each block (and what value remains). But it worked wonderfully for us.

ygra 13y ago

Some people solve this by throwing hardware (and dice!) at it: http://gamesbyemail.com/News/DiceOMatic http://gamesbyemail.com/News/DiceOMatic :-)

herokusaki 13y ago

Fascinating. I wonder if visualizing the dice roll could help. If you don't have ethical objections to it you could also A/B test biased dice (say, biased away from 1 and 20) for complaints (give a different contact email address to players who get biased dice) or instead show the players the distribution of the last 100 rolls.

Udo 13y ago
That's not really possible for a lot of reasons. First, the roller is absolutely anonymous. There are basically three major functions the site performs: just rolling some dice according to user input, an API taking HTTP requests answering in JSON, and a chat room feature that has a dice roller bot. It's not possible to identify individual players except maybe in the chat rooms (though they're not really authenticated there either). I do sometimes get requests to look into chat logs of a particular room over allegations that one player somehow tampered with the results. This happens about once a month. Invariably, the accused user isn't even that lucky, they almost always have bog standard average results. It's just that the other players think this person is unreasonably lucky and they keep this belief up even after I tell them about the data (which they could have calculated themselves by looking at their own chat logs). Second, the core value proposition of the site is its ability to render roleplaying dice codes directly. That means you don't select your dice from a drop down - you enter the code. A simple example would be "3d6+5" for damage or something, but there are lots of different codes for different rules - some of them quite convoluted. It's not feasible to tinker with them in any meaningful way because players use the site in so many different ways.

baby 13y ago

Throwing dices in real life is even less random than a "truly" random function.

nmc 13y ago

You are referring to the common mistake of confusing randomness and uniformity. Your players are thinking: "Dice rolls are equiprobable, so I should roll evenly-distributed results." That only starts being true after a great number of rolls. Random distributions will be uneven and present clumps, strands and voids. For the same reason, during WWII, British intelligence thought that the Germans were bombing specific targets in London, while they were just dropping bombs at random. Source recently posted on HN: http://www.wired.com/wiredscience/2012/12/what-does-randomness-look-like/ http://www.wired.com/wiredscience/2012/12/what-does-randomne...

Udo 13y ago
If you knew how many times I launched into that randomness vs uniformity lecture myself ;) My point was that it's not possible to convince certain people with logic. They see random numbers and something happens to their brains, maybe it's religion. They'll always see oracles or at the very least shady manipulators behind random data.
pixl97 13y ago
https://en.wikipedia.org/wiki/Law_of_large_numbers https://en.wikipedia.org/wiki/Law_of_large_numbers

pessimizer 13y ago

https://en.wikipedia.org/wiki/Representativeness_heuristic https://en.wikipedia.org/wiki/Representativeness_heuristic

raverbashing 13y ago

It should be fun to calculate the chance a RNG is biased based on a die rolling 20 3 times in a roll Similar to that question about biased coins and throwing 10 heads in sequence it was discussed some time ago here.

walshemj 13y ago

It happens at our recent dnd game our mage roiled all 1's on a magic missile 6d4 all 1's

emhart 13y ago

Re: Physical dice. I've gamed a lot over the years, and I don't believe I played with anyone anyone for whom swapping out dice had anything to do with actually effecting randomness/probability, but rather was just a fun way to wish for better luck. And, even then, that move "toward" luck or "away" from bad luck was always tongue-in-cheek. Yet...we still swapped the dice. :)

edraferi 13y ago

Clearly, there is something supernatural afoot: http://www.penny-arcade.com/comic/2014/02/05 http://www.penny-arcade.com/comic/2014/02/05