I decided to roll a liquid core d20 1,000 times and document the results.
Thursday, 13 Mar 2025
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For sale: used d20, barely rolled
There is a great method for checking dice where you float them in a dense liquid. Unbalanced once will reorient with the same side up each time.
Have you calculated the confidence level that it is uniform? (Too sick to do it myself right now, sorry)
I wanna do this with my metal die now. My neighbors are gonna hate me…
this is autism levels of curiosity. and i should know, i have autism and i’ve done similar things multiple times.
[The line from 15-19 connects to 9 at the other side]
), and those all roll hot with their counter side rolling cold.
Any side and it’s opposite should add to 21.
My guy is literally a character from a math problem…
This is a completely true story:
I was looking at this post on my couch and my wife walked up behind me to kiss me on the top of the head and looked over my shoulder at this. She just casually said “What a nerd…” and walked off 😂
To be fair we’re both nerds in our own right and she didn’t mean it in a toxic way. Just thought it was funny 😂
This is actually one of the most interesting things I’ve seen
Switch hands and do it again. Im so serious
I notice that the top four sides (20, 2, 14, 8) all under-perform, and that their complements (1, 19, 7, 13) all over-perform. While the overall looks relatively good, and grouping by number looks good, it might actually be off balance in a way that’s more easily noticed by position
That’s a well made die.
As someone who has gone to similar lengths to make their mind up on something no one can agree on – well played.
Last time was to narrow down the meat for Christmas from 3 meats to one – I didn’t mind, but they couldn’t make their minds up; and left the decider to me.
So I get rolling. 1D6, allocating 2 numbers to each choice in three different ways to work around dice bias. First up 1+2, 3+4, 5+6, followed by 1+4, 2+5, 3+6 finishing with 1+6, 2+5, 3+4. The first two, 50 rolls on each, followed by a first to 25 on the third.
The plan was to eliminate the variable that reached the highest count the most times, then to take it to a first to 25 in a coin flip.
This may have taken me nearly an hour to do, but as I said earlier; a decision had to be reached one way or another.
Statistics are hard – I find it a lot easier to understand empirically.
Here’s some Python code (nested comment) to generate confidence intervals. I repeat your experiment of 1000 rolls (though by the way, unless I mis-transcribed, I count 1002 rolls) 10,000 times. I calculate the expected intervals with a standard confidence level of 5%, but apply a Bonferroni correction (divide by 20, because we test 20 times).
*Darn, I can’t post the plot! Any suggestions how I can add it for those interested? Anyway, the confidence intervals for lower/upper bounds are about 32 and 70.*
The null hypotheses is “the dice is fair”. As others have noted, we don’t reject the null hypothesis, so we can’t say its not fair. But how do we know that you just didn’t do enough rolls? We are trying to show that the dice is fair. You can’t prove a null hypothesis, but you can give a little bit more context about with what level of confidence you “didn’t reject it”.
Given the location of the 95% lines, you can be confident there is a 95% chance that each side rolls between about 3.2% and 7.0% of the time, with a theoretical value of 5%. So your 1000 rolls gives you a level of confidence down to a bias of about 2% between the sides of the d20.
[A little bar chart showing the roll distribution.](https://imgur.com/a/TMcfxO4)
Back when D&D was first popular and good dice were hard to find, most serious players would do something like this to check the balance of their dice.
So results were pretty much as expected
What in the autistic is this.
How long did that take?
Wonderfully balanced. I wonder who the talented dicemaker is.
Lesson: always bet on 9.
Do it 1000 more times and it will be closer to 25% on all of them.
Are you okay?
„I fear not the man who rolled a thousand dice once. I fear the man who rolled one dice a thousand times.“
This is all very interesting but the way you write numbers is beautiful! I’m especially impressed by 7.
Now do that 1,000 times and we’ll have some data to work with!
Ahhh the second set of tally marks in the third bubble of 19. MY EYES!
Good luck finding a normal life someday.
Seems fairly consistent!! Hmmmmm
Bro just aced his Intro to Stats final
Two pairs are high low related.
any smart people can tell me:
how many rolls would it take to make it all 25%
I’m thinking you might be more autistic than I am.
Now sort those low to high. It should come close to a bell curve shape.
This should be on r/mildlyautistic
You got a adhd prescription and showing it off eh?
Further evidence we live in a simulation…
So… well within expectations of random stats.
I’m not very well versed with tabletop RPGs. I’ve never seen a liquid filled die before, it’s pretty cool!
Does it have an effect on the way it rolls?
These are the first steps of insanity, lol
Unemployment activities.
Ah, the universe is working as it should. Nice.