This reminds me of a D&D dice website that went into way too much detail about how they weren't fair and I remember photos of them stacked on top of each other to show the variations in manufacturing.
Reminds me of an encounter on BoardGameArena where the top ranked 7 Wonders Duel player complained there was a randomization bug (the Great Library never offered the science progress token). I thought he was raging (who hasn’t heard a poker player complain about bad luck) but turns out the developer checked the code and did in fact find this was a bug!
> The reason casino dice have such sharp edges is to get the to stop rolling faster with fewer tumbling. The more a die tumbles the more likely it will present any issues with it.
If I understand it correctly, the justification is this: if a die is biased (usually a heavier face), this bias will manifest with a higher chance the longer the die rolls. But if it stops abruptly, for whatever reason (bumping against the edge of the table, other dice, or having a shape that prevents longer roll time, like the casino dice) this bias will be less likely to manifest. Did I get this explanation right?
> The reason casino dice have such sharp edges is to get the to stop rolling faster with fewer tumbling. The more a die tumbles the more likely it will present any issues with it.
No, casino dice are flat-sided cubes because corner curvature could bias the result.
Corner curvature is hard to measure. Cubical dice are easy to check for flatness and dimensions. Gambling regulators have specs for dice: 19mm, flat sides, translucent, balanced, with appropriate tolerances. Casinos usually use dice with serial numbers and logos. Casino dice come in a pack of 5 with all dice in the pack bearing the same serial, to detect substitutions.
Here's a manufacturer of casino dice, with their specs.[1]
Is a 155 throws enough to evaluate bias? Seems more times than I'd like to roll some dice, but not enough to gain enough measurement confidence. By what criteria is the person assigning the traffic light ratings? What about face coplanarity? Get this enthusiast in a metrology lab.!
For role-playing game purposes - not for gambling or serious competition or encryption of your super-valuable secrets - there is a question of what sort of randomization is needed:
* Truly random outcomes: Doesn't hurt
* Psuedo-random outcomes: Good enough?
* Unpredictable but unequally distributed outcomes: As long as nobody can know what will happen, is that sufficient?
* Unknown outcomes: As long as the players can't predict the outcome, that's what counts. If the game manager can avoid bias somehow, why not have them pick the number? Even use family birthdays, old phone numbers, etc., like people do with passwords.
All devices will output unequal distributions for most realistic N, and especially for shorter series. Games are played mostly in shorter series. Does it matter if, over the long run, the device outputs a perfectly equal distribution?
The giveaway is the handling of uncertainty. That's too many decimal places for some of these measurements: 10um (0.01mm) is not reliably measurable by a cheapo caliper, and even trying to do it with a good caliper or micrometer, you'll find that everyday objects simply cannot be reliably straightforwardly measured with that level of precision. (You need cleaning procedures, standardized handling, standardized sampling, etc.) And quoting "4.1g (5.1% too heavy)" versus "4.0g (2.6% too heavy)" is just absurd: that last digit really doesn't mean much. So don't treat it like it does.
For example, on my random first d6 at hand, I get 4.47g from my nice scale and somewhere between 14.82 and 14.85 mm on the first face dimension, depending on how I measure, from my Mitutoyo caliper. I have a micrometer in the shop, but you can see that it'd be pointless to go get it. The next two faces are (14.79 to 14.84) and (14.76 to 14.87), so it's consistently like this.
Likewise, χ² to five decimal places isn't terribly useful... especially since you haven't really described the test you're running....
In general there's a lot of "look at me make measurements" here that might be impressive. There is very little "what is the true value of this measurement, and how well can we assert that", and simply not enough "is this the right thing to be measuring, and how much does that factor matter". That last one is critical: the actual weight of a die is, I think, not important at all. It's weight distribution that matters, so who cares about 0.1g of difference. Unless you're making a batch uniformity claim? But really this evidence just says more about your measuring equipment. And it's well known that different color resins, especially black, white, and red, are pretty differently loaded with pigments, so they have different properties. You can't just expect them to be the same, but the author seems surprised that they aren't.
And then we get to "These dice are safe to use" without any real description of the criteria or threshold. I say "this report is not safe to use (for serious purposes)"!
It's cute, it's a fun little minute to read on the internet this morning. But it's silly, and if my students back in the day or coworkers today sent it to me, they'd be getting red ink and remedial lectures in measurement uncertainty.
The giveaway is the handling of information and curiosity. You argue for throwing both away, and it's not clear why. When the author takes away more decimals than they should, the article becomes useless. When the author leaves in more decimals than they should, I round "with my eyes" to my desired precision. As a bonus, I can take their numbers and spot-check them easily.
The author put up a fun piece on a board game review website and summarized that the dice are fine. You ask what the threshold is, I say use your brain and eyes to pick one. We only need to read this once, not grade 200, so we don't need to invent an arbitrary cutoff.
If you treat students or coworkers in this way, I hope it is clear to them that you respect rubrics more than the actual "Ask a question, gather data, answer it in public" scientific process and that they do not mistake stodgy rules for must-follow procedures. It would be a shame to scare people off from rolling dice on the internet because someone may say there are too few p-values or too many decimal places.
I'm actually the anti-rubric guy! What matters to me is whether your arguments are appropriate to support your conclusions. Not whether you jump through the right hoops.
This guy played it straight: these measurements, this result, that conclusion. But the evidence chain was bad: results couldn't be derived from those measurements, and conclusion couldn't be derived from those results. So I called it out.
This is literally my day job, so I don't really like seeing poorly reasoned research, and maybe I'm more sensitive than most. But if you're going to play it straight, I think you should get it right. If that means you use a lot more weasel words, so be it -- if something is your opinion I can't argue with it. But when you state it as a fact, you better be able to back it up.
Cheating in Warhammer is both the bravest and dumbest thing to try. The people that play that are usually SUPER into the game and absolutely will call you out if there are any tells at all.
Dice aren't assigned to players in this game so even if they were ridiculously biased it wouldn't give any one player and advantage, even if you did roll them more than 3 times in the entire game.
Maybe a player can learn which dice are biased then choose those dice to throw depending on what result would be best for them at that moment? So they gain a slight edge.
Just in case anyone else nerd-sniped themselves this morning... if things fall at the same rate in a vacuum, regardless of their mass, why does it matter if one side of a die is heavier than the rest? I didn't know, and I had to look it up.
It's correct that a biased die will fall without bias. But when it hits the surface and starts tumbling, it tends to rotate around the center of gravity, which will be closer to the heavy side, and the die wants to end up in the orientation with the "lowest gravitational potential energy." If that term isn't part of your lexicon, then think of a Weebil toy.
23 comments
[ 0.95 ms ] story [ 45.6 ms ] thread> The reason casino dice have such sharp edges is to get the to stop rolling faster with fewer tumbling. The more a die tumbles the more likely it will present any issues with it.
If I understand it correctly, the justification is this: if a die is biased (usually a heavier face), this bias will manifest with a higher chance the longer the die rolls. But if it stops abruptly, for whatever reason (bumping against the edge of the table, other dice, or having a shape that prevents longer roll time, like the casino dice) this bias will be less likely to manifest. Did I get this explanation right?
No, casino dice are flat-sided cubes because corner curvature could bias the result. Corner curvature is hard to measure. Cubical dice are easy to check for flatness and dimensions. Gambling regulators have specs for dice: 19mm, flat sides, translucent, balanced, with appropriate tolerances. Casinos usually use dice with serial numbers and logos. Casino dice come in a pack of 5 with all dice in the pack bearing the same serial, to detect substitutions.
Here's a manufacturer of casino dice, with their specs.[1]
[1] https://tcsjohnhuxley.com/product/certified-perfects-dice/
* Truly random outcomes: Doesn't hurt
* Psuedo-random outcomes: Good enough?
* Unpredictable but unequally distributed outcomes: As long as nobody can know what will happen, is that sufficient?
* Unknown outcomes: As long as the players can't predict the outcome, that's what counts. If the game manager can avoid bias somehow, why not have them pick the number? Even use family birthdays, old phone numbers, etc., like people do with passwords.
All devices will output unequal distributions for most realistic N, and especially for shorter series. Games are played mostly in shorter series. Does it matter if, over the long run, the device outputs a perfectly equal distribution?
The giveaway is the handling of uncertainty. That's too many decimal places for some of these measurements: 10um (0.01mm) is not reliably measurable by a cheapo caliper, and even trying to do it with a good caliper or micrometer, you'll find that everyday objects simply cannot be reliably straightforwardly measured with that level of precision. (You need cleaning procedures, standardized handling, standardized sampling, etc.) And quoting "4.1g (5.1% too heavy)" versus "4.0g (2.6% too heavy)" is just absurd: that last digit really doesn't mean much. So don't treat it like it does.
For example, on my random first d6 at hand, I get 4.47g from my nice scale and somewhere between 14.82 and 14.85 mm on the first face dimension, depending on how I measure, from my Mitutoyo caliper. I have a micrometer in the shop, but you can see that it'd be pointless to go get it. The next two faces are (14.79 to 14.84) and (14.76 to 14.87), so it's consistently like this.
Likewise, χ² to five decimal places isn't terribly useful... especially since you haven't really described the test you're running....
In general there's a lot of "look at me make measurements" here that might be impressive. There is very little "what is the true value of this measurement, and how well can we assert that", and simply not enough "is this the right thing to be measuring, and how much does that factor matter". That last one is critical: the actual weight of a die is, I think, not important at all. It's weight distribution that matters, so who cares about 0.1g of difference. Unless you're making a batch uniformity claim? But really this evidence just says more about your measuring equipment. And it's well known that different color resins, especially black, white, and red, are pretty differently loaded with pigments, so they have different properties. You can't just expect them to be the same, but the author seems surprised that they aren't.
And then we get to "These dice are safe to use" without any real description of the criteria or threshold. I say "this report is not safe to use (for serious purposes)"!
It's cute, it's a fun little minute to read on the internet this morning. But it's silly, and if my students back in the day or coworkers today sent it to me, they'd be getting red ink and remedial lectures in measurement uncertainty.
The giveaway is the handling of information and curiosity. You argue for throwing both away, and it's not clear why. When the author takes away more decimals than they should, the article becomes useless. When the author leaves in more decimals than they should, I round "with my eyes" to my desired precision. As a bonus, I can take their numbers and spot-check them easily.
The author put up a fun piece on a board game review website and summarized that the dice are fine. You ask what the threshold is, I say use your brain and eyes to pick one. We only need to read this once, not grade 200, so we don't need to invent an arbitrary cutoff.
If you treat students or coworkers in this way, I hope it is clear to them that you respect rubrics more than the actual "Ask a question, gather data, answer it in public" scientific process and that they do not mistake stodgy rules for must-follow procedures. It would be a shame to scare people off from rolling dice on the internet because someone may say there are too few p-values or too many decimal places.
This guy played it straight: these measurements, this result, that conclusion. But the evidence chain was bad: results couldn't be derived from those measurements, and conclusion couldn't be derived from those results. So I called it out.
This is literally my day job, so I don't really like seeing poorly reasoned research, and maybe I'm more sensitive than most. But if you're going to play it straight, I think you should get it right. If that means you use a lot more weasel words, so be it -- if something is your opinion I can't argue with it. But when you state it as a fact, you better be able to back it up.
A short video about what happened:
https://www.youtube.com/shorts/4ekc9Xwynkc
Only MtG has a more rabid fan base, I think.
It's correct that a biased die will fall without bias. But when it hits the surface and starts tumbling, it tends to rotate around the center of gravity, which will be closer to the heavy side, and the die wants to end up in the orientation with the "lowest gravitational potential energy." If that term isn't part of your lexicon, then think of a Weebil toy.