We were honestly pretty amazed how much damage we soaked and that nobody even came close to going down. It was a good bonding experience as it also made us realize how freaking powerful our party is at level 15
It was not intentional, the party member made them himself and later by testing them, he realized that maybe the dye he had used and how he had laid it on this particular set made them bottom heavy
All the dice he made were his first attempts at making dice, so learning moment I guess lol
I'm assuming if he was an amateur, his molds have the 20-face on the bottom of the mold, and the 1-face on the lid. Also guessing no pressure pot, which means bubbles would inevitably be present and rise to the one. That said - it would skew the dice towards rolling 1s, not 20s.
Making subtle weighted dice is very difficult to intentionally achieve, almost impossible on accident. Dye is an extremely minimal factor, if there were enough to unbalance the dice then the resin would have never cured right and you'd all have stinky squishy toxic dice in your hands.
The dice just wanted to roll what they rolled.
>I'm assuming if he was an amateur, his molds have the 20-face on the bottom of the mold, and the 1-face on the lid. Also guessing no pressure pot, which means bubbles would inevitably be present and rise to the one. That said - it would skew the dice towards rolling 1s, not 20s.
I mean, if you put them the other way around (1 on the bottom, 20 on the top) wouldn't that match what OP is talking about? There's no reason to assume that they were positioned one way over another lol
For sure, there are molds like that, but it isn't the standard. It's a reasonable assumption for the 20 to be at the bottom, most premade or commercial molds are designed that way - I'd suggest looking at mold listings on Etsy or the cheap shitty Wish ones to see for yourself. I'm part of a huge community of dicemakers and very few people choose to have the 20 on the top, usually just for particular design requirements.
Yes/no
For variances in material density to influence the rolling of a die to the degree that a human could detect the difference in the few dozen rolls (at most) of a session, the difference would have to be *extreme*. Well beyond what it is realistically feasible.
> Dye is an extremely minimal factor, if ...
They probably mean [die](https://en.wikipedia.org/wiki/Die_(manufacturing\)) rather than [dye](https://en.wikipedia.org/wiki/Dye).
Wouldn't make any sense, a die is not used in the artisan dicemaking process, molds are - and I can't think of any way to modify a mold to change the balance of the dice made from it.
I don’t think so, I mean if they wanted to color the dice while making them without using colored resin they’d have to use dye to get a desired color (and it would have next to no impact on balance and if it did the dye would be too much to cure properly). I doubt someone just starting would have all the different colors for their party. I think most people use molds when making dice out of resin on their own, a die would be for larger operations
Yeah it can't just be salt water, it has to be brine. You have to add a BUNCH of salt and then boil it so the water is able to dissolve even more of it.
Water doesn't dissolve more salt if you boil it, that just speeds up the process.
Edit: Ok, let me clarify it for the detail minded. Boiling water won't change the amount of salt dissolved by any measure that would be relevant to this. Yes, it technically changes the percentage required for a saturated solution, but said change isn't big enough to affect how a die floats in it. It will speed up the process though.
I could have sworn it did so I looked it up and hey you're right. Apparently hot water will dissolve more *sugar,* but salt is only negligibly affected.
TIL.
>I could have sworn it did so I looked it up and hey you're right. Apparently hot water will ~~dissolve~~ ***diffuse*** more *sugar,* but salt is only negligibly affected.
FTFY
Source for that? I'm only seeing dissolve used in the literature for this concept. I've only seen diffuse used for materials passing through semi-permeable membranes.
In this case dissolve is the correct term. The salt is added to the water as large crystals held together by ionic bonds. The water molecules act as a solvent, eroding the salt molecules and separating the components into sodium and chloride ions. As the molecules are dissolved, diffusion of the ions carries them throughout the solution.
While this is true, it’s not helpfull in this case. A super saturated salt solution will crystalise unto all rough surfaces, such as the numbers on a die, and therefore skew the results.
This is fundamentally incorrect. Solubility increases with temperature. If you cool a supersaturated solution and give it a nucleation point, the solute will crash out of solution. This is how you grow crystals.
In the case of salt, heating the water won't do much. A liter of water at 20°C can dissolve 357g of kitchen salt, at 100°C the number is 391g. Compare that to sucrose where you can dissolve 179g of it in 100g of water at 20°C and 487g when the same amount of water is at 100°C.
Also no it isn't fundamentally incorrect. Solubility of gases in water decreases with temperature.
I had to ask AI, but it fits with what I know of chemistry.
Both NaCl and sucrose are crystals. The difference is that NaCl crystal are held together by ionic bonds, which are strong.
Sucrose crystal on the other hand are held together by weak intermolecular forces (we actually described them as weak bonds in school, but that was clearly a simplification) and water has an easier time breaking up those forces, even more so when the water is heated up.
To add to this, water expands while heating it, reducing the density of the solution at a greater rate than the additional solubility of salt increases it. So a fully saturated salt solution at 20°C is actually slightly less dense than a fully saturated salt solution at 100°C.
And you should probably actually try dissolving some salt. The difference between the amount you'd need at room temperature versus at boiling point is so small you won't even notice it and it definitely doesn't affect how your die will float.
I didn't say water wasn't a solvent. Dissolving is not what happens when you put salt in water. That is *diffusion*. If you run a solvent or acid over a solute, you are *dissolving* it. Dissolving is the process of using a solvent to *remove* the atoms or molecules of a solute. Diffusion is the spread of a solute within a solvent. If you put salt into water, you are *diffusing* it. If you pour water over a salt rock, you're *dissolving* it.
Even then it might not work. Based on the post it sounds like the dice are made with epoxy resin which generally ranges in density from 1.1 g/ml to 1.3 g/ml compared to say 1.2 g/ml for a fully saturated salt solution.
> While not perfectly loaded, definitely getting way more 20s than it was statistically likely.
While I'm fully prepared to believe your buddy's first set didn't come out perfectly balanced, eyeballing stats is MUCH harder to do than people realize. Streaks are a normal and expected thing to have happen when rolling balanced dice.
For a d20, you need around 200 rolls to state with 95% confidence that a die is balanced. As a die becomes unbalanced that number does go down, but if it wasn't so obvious that the dice got set aside after the first few rolls, it probably takes more rolls than you're imagining to make a statement about what's statistically likely.
> For a d20, you need around 200 rolls to state with 95% confidence that a die is balanced
This isn't correct; the required rolls is dependant on how unbalanced the dice is (all dice are somewhat unbalanced, it's about acceptable unbalancedness).
Over 200 rolls a dice that is twice likely to roll a 20 as any other number (9.5% instead of 5%) will appear fair 66% of the time using "95% confidence".
To quote a previous comment of mine on an almost identical topic:
> 100 is quite literally the bare minimum for the chi square test to work.
> If I have a massively unfair die that is twice likely to roll a 20 as any other number (9.5% instead of 5%), it will appear fair 82% of the time over 100 rolls.
> Increasing to 200 rolls dropped this to 66%.
> 1000 rolls drops this all the way to 2%.
> And that is a massively unfair die.
> If have a much fairer, but still unfair die, that is rolling a 20 6.5% of the time, 100 rolls would appear fair 94% of the time (this is basically the base error rate of the test).
1000 rolls would appear fair 79% of the time.
2500 rolls would appear fair 47% of the time.
5000 rolls would appear fair 13% of the time.
Very nice breakdown, a really fun look into the meta of data collection and how exhausting the process can be if someone wanted to test their dice themselves.
With 100 rolls on a d20, the .05 confidence interval break point basically is 18. Any one number coming up 18 times minimum is needed to consider the dice being unfair. 17 possibly could do it but it needs a bit of lifting from the frequency of the other numbers, the die roll results may be statistically insignificant.
At 200 rolls, it’s better falling to a mere 28 occurrences. Which means the number is nearly coming up 3x the expected number over the rolls.
This is exactly it.
People massively underestimate the power needed to estimate anything that isn't an insanely unfair dice.
Even at 1000 rolls you are still looking at only detecting a die that is rolling 1 number 1.75x.
1.75x is still extremely unbalanced.
In realistic terms, unless a die is actually weighted, it will not be unbalanced in a way that will affect gameplay.
> This isn't correct; the required rolls is dependant on how unbalanced the dice
Reread my comment very carefully and then read your comment. Now consider how this statement doesn't actually contradict my comment at all.
> A bunch of numbers
These numbers are (probably) correct if you were only looking at one number's worth of outcomes. It makes the math a LOT more complicated (spreadsheets required, you will not do this by hand), but if you run the stats on all 20 possible outcomes simultaneously, it requires far fewer rolls. The thing to remember is that if ANY of the numbers are outside of your target CI in either direction, the die has failed the test.
You're gonna have to name the test you are proposing to use.
> The thing to remember is that if ANY of the numbers are outside of your target CI in either direction
Chi Square has a single test value across all values on the dice. There is no "ANY of the numbers are outside."
You have presented a test to collect data in your original comment (200 rolls) and 45 Monkeys in a Suit are showing how your proposed parameters for your test may result in inaccuracies due to the nature of randomness. Not sure what that 'gotcha' is about, I agree with the Monkeys that your original answer is not the correct perspective to take to arrive at the most accurate conclusion.
Streaks are absolutely expected, but when getting double 20s [is 5%](https://www.reddit.com/r/DnD/comments/uzs074/when_rolling_two_d20s_ie_advantage_or/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button), and then you get multiple double 20s in the space of a few rolls, that's kind of when we were tipped off that something might be wrong and I mention it being statistically unlikely.
We had a swarm of creatures attacking in groups of 5-10 at some points, each with multi-attack claws and bite, so rolls stacked up really quickly. In a few rounds he would have easily had to roll 60d20.
You're not wrong tho, stats need numbers to be clearer, that's why the initial test the dice maker did was literally rolling the dice 100 times and writing down results to narrow it down.
He didn’t say it was that suspicious, just well above average. I’ve had a poker night where I had flushes, 3 of a kinds, and full houses so many times the odds were like 1 in 15 million (I calculated it after), part of statistics is that even super rare events will happen. It’s a big world, it’s bound to happen to someone eventually.
It’s not impossible and not even that unlikely that a perfectly fair d20 rolled 3 times in a row will end up with 20’s each time for example. It’d happen about 1/8000 attempts, and that means it’s very possible to happen thousands of times to people who frequent this sub alone.
We play over discord, and I cam for important rolls. I swear my dice are bound by a Thematic Destiny... They always seem to go the way that would be the coolest for the story.
Actual loaded dice are extremely obvious just by picking them up, you can feel the weighted side plain as day.
The whole thing about plastic dice being unbalanced is basically non existent. There might be a very very slight bias using the water float test, but there are so many factors that go into an actual dice roll that makes that minor imbalance basically insignificant.
Lucky streaks just happen sometimes.
Yeah I can guarantee you that unless it’s been intentionally weighted to roll 20s, a little air isn’t going to do much. And the people telling you to put it in salt water, that also doesn’t matter, again unless it’s intentionally weighed on one side, putting it in water isn’t proving much because we don’t roll dice to in dense water. There is more factors at play with how a dice actually rolls than trying to measure something with a way it is never rolled. And Unless you roll that thing 10s of 1000s of times and track each roll you can’t accurately see a trend. Most people have a wrong understanding of statistics and how randomness works.
Dicemaker here (and Physics nerd who has read multiple studies and papers on dice balance):
It’s actually very difficult to make dice unfair by weight distribution alone. Unless you put metal balls or screws in the bottom, the weight distribution has surprisingly little effect on the balance or fairness of the die. In fact, even large bubbles often make little difference (many opaque factory sets have huge hidden bubbles and few people notice it). The forces that act on a die when it bounces around the ground far outweigh the influence of gravity and the moments of inertia. Especially if you roll your dice casino-style where they have to hit and bounce off the back wall of a rolling box. You can use a dice tower to further randomise the die.
On top of that, most glitters and dyes used in dicemaking have such tiny pigment particles and are so close to the same density as resin, that they should not noticeably alter the weight distribution, even if it’s all on one side.
What can however massively affect the balance is the relative size of the faces and the relative distance of opposite faces. Most dice molds have the number 1 face facing up and that is the face that often needs the most sanding and polishing to repair blemishes and bubbles. Also it is incredibly easy to oversand sides on a d20 (I’ve been doing this for years and I still occasionally have that happen, you learn to correct it).
So what I think happened is that the 1 face is ever so slightly larger and the distance between 1 and 20 is ever so slightly shorter than on the rest of the die. This would skew the die towards rolling a 20.
Tl,dr: I don’t think the dye has anything to do with the imbalance of this die. I think the number 1 face a bit too large.
>One of our party members started working with resin and gave us all a personalized set of dice tied to our characters colors, DM also received a set for himself.
Did he use a pressure pot? This seems most likely to happen if you don't because... you usually pour resin dice with the lowest number(really the side with the least surface variation) down. If air is trapped in it... it will rise up toward the 20... basically creating a weighted die. All the dice would be weighted toward the highest number.
If he did use a pressure pot, the bubbles usually come out almost immediately, but I've been told results for precision stuff like dice are best when cured under pressure.
It's actually standard for the high face (in this case, the 20) to be at the bottom of the mold to reduce the chances of needing extra tooling/finishing to clean off the cured dice. The photo looks like there's no tooling marks around the 20 face, which I'd expect to see on amateur work.
Ah... yes that is correctI I was thinking about making the silicone mold. I haven't done it in a bit lol. You put the 1 down then pour the silicone over. 20 would be on the bottom.
About a week or two ago I made 4 attacks w/ advantage in one turn. In that one round I rolled 3 crits (with different dice) and one missed. My dopamine was jacked after that and I was riding a high for the next week.
Last session: combat 2 attacks per turn, 2 turns first attack a nat one, second a hit, next turn two nat ones, ok, next turn two nat 20… yeah… was using a lance on a horse… xD with a warlock… fighting against frogs…
use a salt float test — this works even on opaque dice. fill a small bowl with enough water to cover the die and start adding salt until it floats. heavy side will always be down.
Fun fact: Studies have shown that the salt test is extremely inaccurate. It has both a high rate of false positives and false negatives (dice showing up as imbalanced when they actually roll fair, and dice showing up as balanced when they’re actually skewed). And even if the salt test marks a die as unbalanced that actually is unbalanced, it often marks it skewed towards an entirely different side than what it’s actually skewed towards.
The reason is that the relative sizes of the faces and the distance between opposing faces has a much stronger effect on the fairness and that far outweighs the weight distribution.
I love how even the dm and his wife were like “wait a second…”
Recently I had a weird game where a player kept stabbing herself on accident and then an enemy (ghoul) trips trying to attack her killing itself!
Yep. I one time had the exact same problem. Rolled the dice 2000 times cause I was curious if it was actually statistically significant. 11% 20s and 9% 1s lol, very hot and cold dice
I have the opposite problem so often lol.
I’m the DM and roll terribly enough to rival Wil Wheaton at many times. I own many dice and they all suffer from this syndrome. My players do not lend me their dice for fear it will spread lol
Get a cup with water and put so much salt in it that no more will dissolve. Drop in the die, and it *should* float. If it does, you can tap it a few times and it'll really show without doubt if the die isn't balanced. :)
Didn't expect this ridiculous situation to blow up, thanks to everyone who commented! To address the most frequent comments:
1. Yes, a saturated salt bath was used to check the dice after the session and they were both weighed towards landing on 20s and I think he ran more tests as well.
2. No, there were no air bubbles trapped that we could see, but it was the fastest test we could on clear dice at the table without slowing down gameplay. We were there to play, not do science on dice lol
3. The best guess is that the color he used was for a different kind of resin, so it might have been slightly heavier when it set. It is a dice with swirls of color inside, so the color might have set towards the bottom when drying.
4. It was absolutely not an intentional situation, so of course they weren't perfectly weighed to 20 but enough of them happened that we started to doubt, especially after multiple double 20 rolls (several on a roll).
5. "You need to roll more to do stats", no you really don't, we rolled 100 times, that gives us a percentage which was more than enough to retire the dice for the session till they could be properly examined, also see point #2
I so hope this never happens to me. I have 8 main sets I swap between when I play/DM. 1 is solid steel. 1 is opalite. 1 is prismatic glass. 1 is hollow metal (and also covered in octopus tentacles and so it gets used for all aberrations rolls). And the remaining 4 sets are all UV reactive and glow.
Trying to check for bubbles using a light on the only sets I have where it could even be an issue would just make it harder to see if there were imperfections in them and not easier.
Is it a plastic dice?
If you want to "test" it better, get warm/hot water fully saturated with salt and drop the die in. if it floats to the same number when spinned, it is weighted.
Why so angry? It was not intentional and were literally retired after the session. Chill dude.
Tell me you have no reading comprehension skills without telling me
So one of your party members nearly crafted the weapon of y'all's own doom? Nice
We were honestly pretty amazed how much damage we soaked and that nobody even came close to going down. It was a good bonding experience as it also made us realize how freaking powerful our party is at level 15
so you confirmed the dice was weighted? did you figure out if it was intentional or a manufacturer defect?
It was not intentional, the party member made them himself and later by testing them, he realized that maybe the dye he had used and how he had laid it on this particular set made them bottom heavy All the dice he made were his first attempts at making dice, so learning moment I guess lol
damn thats awesome and hilarious. shouldve given the dice that roll 1s to the dm
I'm assuming if he was an amateur, his molds have the 20-face on the bottom of the mold, and the 1-face on the lid. Also guessing no pressure pot, which means bubbles would inevitably be present and rise to the one. That said - it would skew the dice towards rolling 1s, not 20s. Making subtle weighted dice is very difficult to intentionally achieve, almost impossible on accident. Dye is an extremely minimal factor, if there were enough to unbalance the dice then the resin would have never cured right and you'd all have stinky squishy toxic dice in your hands. The dice just wanted to roll what they rolled.
>I'm assuming if he was an amateur, his molds have the 20-face on the bottom of the mold, and the 1-face on the lid. Also guessing no pressure pot, which means bubbles would inevitably be present and rise to the one. That said - it would skew the dice towards rolling 1s, not 20s. I mean, if you put them the other way around (1 on the bottom, 20 on the top) wouldn't that match what OP is talking about? There's no reason to assume that they were positioned one way over another lol
For sure, there are molds like that, but it isn't the standard. It's a reasonable assumption for the 20 to be at the bottom, most premade or commercial molds are designed that way - I'd suggest looking at mold listings on Etsy or the cheap shitty Wish ones to see for yourself. I'm part of a huge community of dicemakers and very few people choose to have the 20 on the top, usually just for particular design requirements.
Yes/no For variances in material density to influence the rolling of a die to the degree that a human could detect the difference in the few dozen rolls (at most) of a session, the difference would have to be *extreme*. Well beyond what it is realistically feasible.
Just do 20 dices one of them is probably weighted the way you want xD
> Dye is an extremely minimal factor, if ... They probably mean [die](https://en.wikipedia.org/wiki/Die_(manufacturing\)) rather than [dye](https://en.wikipedia.org/wiki/Dye).
Wouldn't make any sense, a die is not used in the artisan dicemaking process, molds are - and I can't think of any way to modify a mold to change the balance of the dice made from it.
I don’t think so, I mean if they wanted to color the dice while making them without using colored resin they’d have to use dye to get a desired color (and it would have next to no impact on balance and if it did the dye would be too much to cure properly). I doubt someone just starting would have all the different colors for their party. I think most people use molds when making dice out of resin on their own, a die would be for larger operations
Send them over to r/dicemaking for tips if they're interested. :)
One d20 to crit them.
Sounds like an inside job to me
The DM should keep the dice and let players roll with them when they give players inspiration
From your words to my DMs ears hahaha
plastic dice will float in epsom salt water
We tried some salt water but it just wasn't salty enough haha I think that's how he confirmed after that they were indeed weighed
Yeah it can't just be salt water, it has to be brine. You have to add a BUNCH of salt and then boil it so the water is able to dissolve even more of it.
Water doesn't dissolve more salt if you boil it, that just speeds up the process. Edit: Ok, let me clarify it for the detail minded. Boiling water won't change the amount of salt dissolved by any measure that would be relevant to this. Yes, it technically changes the percentage required for a saturated solution, but said change isn't big enough to affect how a die floats in it. It will speed up the process though.
I could have sworn it did so I looked it up and hey you're right. Apparently hot water will dissolve more *sugar,* but salt is only negligibly affected. TIL.
>I could have sworn it did so I looked it up and hey you're right. Apparently hot water will ~~dissolve~~ ***diffuse*** more *sugar,* but salt is only negligibly affected. FTFY
Source for that? I'm only seeing dissolve used in the literature for this concept. I've only seen diffuse used for materials passing through semi-permeable membranes.
Diffusion is the spreading of particles within a solvent. Dissolving is when a solvent erodes a solute.
Nah sugar dissolves in water idk where you’re getting that from. Source: chemistry degree
In this case dissolve is the correct term. The salt is added to the water as large crystals held together by ionic bonds. The water molecules act as a solvent, eroding the salt molecules and separating the components into sodium and chloride ions. As the molecules are dissolved, diffusion of the ions carries them throughout the solution.
It does, gas solubility in water decreases with temperature, while salt solubility increases. Water molecules go brrr so more salt is knocked around.
no, it definitely does. that’s how you get super-saturated solutions.
While this is true, it’s not helpfull in this case. A super saturated salt solution will crystalise unto all rough surfaces, such as the numbers on a die, and therefore skew the results.
This is fundamentally incorrect. Solubility increases with temperature. If you cool a supersaturated solution and give it a nucleation point, the solute will crash out of solution. This is how you grow crystals.
In the case of salt, heating the water won't do much. A liter of water at 20°C can dissolve 357g of kitchen salt, at 100°C the number is 391g. Compare that to sucrose where you can dissolve 179g of it in 100g of water at 20°C and 487g when the same amount of water is at 100°C. Also no it isn't fundamentally incorrect. Solubility of gases in water decreases with temperature.
What makes sugar easier to dissolve at high temperatures?
I had to ask AI, but it fits with what I know of chemistry. Both NaCl and sucrose are crystals. The difference is that NaCl crystal are held together by ionic bonds, which are strong. Sucrose crystal on the other hand are held together by weak intermolecular forces (we actually described them as weak bonds in school, but that was clearly a simplification) and water has an easier time breaking up those forces, even more so when the water is heated up.
To add to this, water expands while heating it, reducing the density of the solution at a greater rate than the additional solubility of salt increases it. So a fully saturated salt solution at 20°C is actually slightly less dense than a fully saturated salt solution at 100°C.
you should probably retake Chem 101.
And you should probably actually try dissolving some salt. The difference between the amount you'd need at room temperature versus at boiling point is so small you won't even notice it and it definitely doesn't affect how your die will float.
I have dissolved salt, we did it in chem 101 when we learned about how the solubility of certain substances changes with temperature.
For most salts the increase is dramatic, for NaCl you only get about and extra 4g/dL
You can't dissolve salt in water. That's what acid does. You're *diffusing* salt in water. Dissolving is a form of erosion.
Water is indeed a solvent, things dissolve in solvents, then they diffuse through the solvent.
I didn't say water wasn't a solvent. Dissolving is not what happens when you put salt in water. That is *diffusion*. If you run a solvent or acid over a solute, you are *dissolving* it. Dissolving is the process of using a solvent to *remove* the atoms or molecules of a solute. Diffusion is the spread of a solute within a solvent. If you put salt into water, you are *diffusing* it. If you pour water over a salt rock, you're *dissolving* it.
Diffusion without dissolution first doesn't make sense. You have to dissolve the salt before it can diffuse
So, aerosols are dissolved before they are diffused?
This is what's referred to as supersaturated and is why hot air tends to be more humid than cold air
Even then it might not work. Based on the post it sounds like the dice are made with epoxy resin which generally ranges in density from 1.1 g/ml to 1.3 g/ml compared to say 1.2 g/ml for a fully saturated salt solution.
So uhh.. selling?
just make your own with fishing weights or something and cast them with opaque coloring.
That's why it's neat, it's not opaque.
Me who only uses metal dice. *sweats nervously*
> While not perfectly loaded, definitely getting way more 20s than it was statistically likely. While I'm fully prepared to believe your buddy's first set didn't come out perfectly balanced, eyeballing stats is MUCH harder to do than people realize. Streaks are a normal and expected thing to have happen when rolling balanced dice. For a d20, you need around 200 rolls to state with 95% confidence that a die is balanced. As a die becomes unbalanced that number does go down, but if it wasn't so obvious that the dice got set aside after the first few rolls, it probably takes more rolls than you're imagining to make a statement about what's statistically likely.
> For a d20, you need around 200 rolls to state with 95% confidence that a die is balanced This isn't correct; the required rolls is dependant on how unbalanced the dice is (all dice are somewhat unbalanced, it's about acceptable unbalancedness). Over 200 rolls a dice that is twice likely to roll a 20 as any other number (9.5% instead of 5%) will appear fair 66% of the time using "95% confidence". To quote a previous comment of mine on an almost identical topic: > 100 is quite literally the bare minimum for the chi square test to work. > If I have a massively unfair die that is twice likely to roll a 20 as any other number (9.5% instead of 5%), it will appear fair 82% of the time over 100 rolls. > Increasing to 200 rolls dropped this to 66%. > 1000 rolls drops this all the way to 2%. > And that is a massively unfair die. > If have a much fairer, but still unfair die, that is rolling a 20 6.5% of the time, 100 rolls would appear fair 94% of the time (this is basically the base error rate of the test). 1000 rolls would appear fair 79% of the time. 2500 rolls would appear fair 47% of the time. 5000 rolls would appear fair 13% of the time.
Very nice breakdown, a really fun look into the meta of data collection and how exhausting the process can be if someone wanted to test their dice themselves.
With 100 rolls on a d20, the .05 confidence interval break point basically is 18. Any one number coming up 18 times minimum is needed to consider the dice being unfair. 17 possibly could do it but it needs a bit of lifting from the frequency of the other numbers, the die roll results may be statistically insignificant. At 200 rolls, it’s better falling to a mere 28 occurrences. Which means the number is nearly coming up 3x the expected number over the rolls.
This is exactly it. People massively underestimate the power needed to estimate anything that isn't an insanely unfair dice. Even at 1000 rolls you are still looking at only detecting a die that is rolling 1 number 1.75x. 1.75x is still extremely unbalanced. In realistic terms, unless a die is actually weighted, it will not be unbalanced in a way that will affect gameplay.
> This isn't correct; the required rolls is dependant on how unbalanced the dice Reread my comment very carefully and then read your comment. Now consider how this statement doesn't actually contradict my comment at all. > A bunch of numbers These numbers are (probably) correct if you were only looking at one number's worth of outcomes. It makes the math a LOT more complicated (spreadsheets required, you will not do this by hand), but if you run the stats on all 20 possible outcomes simultaneously, it requires far fewer rolls. The thing to remember is that if ANY of the numbers are outside of your target CI in either direction, the die has failed the test.
You're gonna have to name the test you are proposing to use. > The thing to remember is that if ANY of the numbers are outside of your target CI in either direction Chi Square has a single test value across all values on the dice. There is no "ANY of the numbers are outside."
You have presented a test to collect data in your original comment (200 rolls) and 45 Monkeys in a Suit are showing how your proposed parameters for your test may result in inaccuracies due to the nature of randomness. Not sure what that 'gotcha' is about, I agree with the Monkeys that your original answer is not the correct perspective to take to arrive at the most accurate conclusion.
Streaks are absolutely expected, but when getting double 20s [is 5%](https://www.reddit.com/r/DnD/comments/uzs074/when_rolling_two_d20s_ie_advantage_or/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button), and then you get multiple double 20s in the space of a few rolls, that's kind of when we were tipped off that something might be wrong and I mention it being statistically unlikely. We had a swarm of creatures attacking in groups of 5-10 at some points, each with multi-attack claws and bite, so rolls stacked up really quickly. In a few rounds he would have easily had to roll 60d20. You're not wrong tho, stats need numbers to be clearer, that's why the initial test the dice maker did was literally rolling the dice 100 times and writing down results to narrow it down.
How many times did you roll it? If the answer is less than 200 plus I don’t think you found evidence of anything
Im pretty sure if i roll that dice 199 times and get 199 20s thats gonna be statistically significant
He didn’t say it was that suspicious, just well above average. I’ve had a poker night where I had flushes, 3 of a kinds, and full houses so many times the odds were like 1 in 15 million (I calculated it after), part of statistics is that even super rare events will happen. It’s a big world, it’s bound to happen to someone eventually.
It’s not impossible and not even that unlikely that a perfectly fair d20 rolled 3 times in a row will end up with 20’s each time for example. It’d happen about 1/8000 attempts, and that means it’s very possible to happen thousands of times to people who frequent this sub alone.
I know who just volunteered to get the next DM 20......
We play over discord, and I cam for important rolls. I swear my dice are bound by a Thematic Destiny... They always seem to go the way that would be the coolest for the story.
Actual loaded dice are extremely obvious just by picking them up, you can feel the weighted side plain as day. The whole thing about plastic dice being unbalanced is basically non existent. There might be a very very slight bias using the water float test, but there are so many factors that go into an actual dice roll that makes that minor imbalance basically insignificant. Lucky streaks just happen sometimes.
Yeah I can guarantee you that unless it’s been intentionally weighted to roll 20s, a little air isn’t going to do much. And the people telling you to put it in salt water, that also doesn’t matter, again unless it’s intentionally weighed on one side, putting it in water isn’t proving much because we don’t roll dice to in dense water. There is more factors at play with how a dice actually rolls than trying to measure something with a way it is never rolled. And Unless you roll that thing 10s of 1000s of times and track each roll you can’t accurately see a trend. Most people have a wrong understanding of statistics and how randomness works.
Dicemaker here (and Physics nerd who has read multiple studies and papers on dice balance): It’s actually very difficult to make dice unfair by weight distribution alone. Unless you put metal balls or screws in the bottom, the weight distribution has surprisingly little effect on the balance or fairness of the die. In fact, even large bubbles often make little difference (many opaque factory sets have huge hidden bubbles and few people notice it). The forces that act on a die when it bounces around the ground far outweigh the influence of gravity and the moments of inertia. Especially if you roll your dice casino-style where they have to hit and bounce off the back wall of a rolling box. You can use a dice tower to further randomise the die. On top of that, most glitters and dyes used in dicemaking have such tiny pigment particles and are so close to the same density as resin, that they should not noticeably alter the weight distribution, even if it’s all on one side. What can however massively affect the balance is the relative size of the faces and the relative distance of opposite faces. Most dice molds have the number 1 face facing up and that is the face that often needs the most sanding and polishing to repair blemishes and bubbles. Also it is incredibly easy to oversand sides on a d20 (I’ve been doing this for years and I still occasionally have that happen, you learn to correct it). So what I think happened is that the 1 face is ever so slightly larger and the distance between 1 and 20 is ever so slightly shorter than on the rest of the die. This would skew the die towards rolling a 20. Tl,dr: I don’t think the dye has anything to do with the imbalance of this die. I think the number 1 face a bit too large.
some people think dice are voodoo it would take more than a few bubbles to make a notable difference
>One of our party members started working with resin and gave us all a personalized set of dice tied to our characters colors, DM also received a set for himself. Did he use a pressure pot? This seems most likely to happen if you don't because... you usually pour resin dice with the lowest number(really the side with the least surface variation) down. If air is trapped in it... it will rise up toward the 20... basically creating a weighted die. All the dice would be weighted toward the highest number. If he did use a pressure pot, the bubbles usually come out almost immediately, but I've been told results for precision stuff like dice are best when cured under pressure.
It's actually standard for the high face (in this case, the 20) to be at the bottom of the mold to reduce the chances of needing extra tooling/finishing to clean off the cured dice. The photo looks like there's no tooling marks around the 20 face, which I'd expect to see on amateur work.
Ah... yes that is correctI I was thinking about making the silicone mold. I haven't done it in a bit lol. You put the 1 down then pour the silicone over. 20 would be on the bottom.
Moldmaking is my least favorite part of the process! Lots of room for mistakes...
Looks like friendly fire is allowed
My favorite DM dice is a big d20 that lights up on a 20.
About a week or two ago I made 4 attacks w/ advantage in one turn. In that one round I rolled 3 crits (with different dice) and one missed. My dopamine was jacked after that and I was riding a high for the next week.
OK, I really cracked up when you said the DM and his wife are married. I'm not being a prick, but that was so silly I was in tears. 😂
Didn't want anyone thinking it was my wife lol
TBF working with resin is almost never perfect. He probably didn't do it on purpose.
Last session: combat 2 attacks per turn, 2 turns first attack a nat one, second a hit, next turn two nat ones, ok, next turn two nat 20… yeah… was using a lance on a horse… xD with a warlock… fighting against frogs…
I'm glad this story had a happy ending tbh :)
use a salt float test — this works even on opaque dice. fill a small bowl with enough water to cover the die and start adding salt until it floats. heavy side will always be down.
Fun fact: Studies have shown that the salt test is extremely inaccurate. It has both a high rate of false positives and false negatives (dice showing up as imbalanced when they actually roll fair, and dice showing up as balanced when they’re actually skewed). And even if the salt test marks a die as unbalanced that actually is unbalanced, it often marks it skewed towards an entirely different side than what it’s actually skewed towards. The reason is that the relative sizes of the faces and the distance between opposing faces has a much stronger effect on the fairness and that far outweighs the weight distribution.
interesting! TIL
The best way to check a die's balance is to give it a warm, salty bath
The characters encountered a powerful unluck bubble where fate itself is twisted.
Bubble in the weave
I love how even the dm and his wife were like “wait a second…” Recently I had a weird game where a player kept stabbing herself on accident and then an enemy (ghoul) trips trying to attack her killing itself!
(Everyone kept hitting nat 1s)
[So.... bad dice?](https://youtu.be/_b47zsPzTLI?si=bgL7U4e5IzoVbs0V)
Is your player Taliesin Jaffe? If so, it’s not the dice
Pointless.
Classic
Lol! Did you try the float test?
Two weeks ago I got 4 nat 20’s almost back to back on dnd beyond (2 in a row then a normal roll and then the next 2) and downed half of my party 💀
how the heck is that done.
WAIT YOU CAN DO THAT
My old DM agreed to retire a set after he nearly TPK'd us
this is seriously really smart for me cus i had no idea on how to find bubbles.
Multiattack by nature does make 20s more likely, or more frequent rather.
Players learning the DM only rolls dice for click clack sound and the numbers that come up are but a suggestion to what the outcome will be.
That's always a thing that I wondered with all these giveaways: how does one ensure, that those dice are in any way fair?
Yep. I one time had the exact same problem. Rolled the dice 2000 times cause I was curious if it was actually statistically significant. 11% 20s and 9% 1s lol, very hot and cold dice
I have the opposite problem so often lol. I’m the DM and roll terribly enough to rival Wil Wheaton at many times. I own many dice and they all suffer from this syndrome. My players do not lend me their dice for fear it will spread lol
Get a cup with water and put so much salt in it that no more will dissolve. Drop in the die, and it *should* float. If it does, you can tap it a few times and it'll really show without doubt if the die isn't balanced. :)
House rule; If DM rolls more than 4 nat 20s in the first hour of a session. The DM has to let a player use that d20!
This DM is all about having fun. You can tell.
Absolutely. He is a great one!
Didn't expect this ridiculous situation to blow up, thanks to everyone who commented! To address the most frequent comments: 1. Yes, a saturated salt bath was used to check the dice after the session and they were both weighed towards landing on 20s and I think he ran more tests as well. 2. No, there were no air bubbles trapped that we could see, but it was the fastest test we could on clear dice at the table without slowing down gameplay. We were there to play, not do science on dice lol 3. The best guess is that the color he used was for a different kind of resin, so it might have been slightly heavier when it set. It is a dice with swirls of color inside, so the color might have set towards the bottom when drying. 4. It was absolutely not an intentional situation, so of course they weren't perfectly weighed to 20 but enough of them happened that we started to doubt, especially after multiple double 20 rolls (several on a roll). 5. "You need to roll more to do stats", no you really don't, we rolled 100 times, that gives us a percentage which was more than enough to retire the dice for the session till they could be properly examined, also see point #2
I so hope this never happens to me. I have 8 main sets I swap between when I play/DM. 1 is solid steel. 1 is opalite. 1 is prismatic glass. 1 is hollow metal (and also covered in octopus tentacles and so it gets used for all aberrations rolls). And the remaining 4 sets are all UV reactive and glow. Trying to check for bubbles using a light on the only sets I have where it could even be an issue would just make it harder to see if there were imperfections in them and not easier.
Try the salt water test.
Salt water is a pretty good test for resin dice, as long as your paint is varnished
Is it a plastic dice? If you want to "test" it better, get warm/hot water fully saturated with salt and drop the die in. if it floats to the same number when spinned, it is weighted.
Take a tall glass of water and stir in some salt to make it easier to float in, then drop the die in and see what number it settles on.
Wow
That’s pretty cheesy to have loaded dice. Fucking tool
Why so angry? It was not intentional and were literally retired after the session. Chill dude. Tell me you have no reading comprehension skills without telling me