
How fair are your dice? - sohkamyung
http://arstechnica.co.uk/the-multiverse/2016/08/how-fair-is-your-d20/
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speeder
I bought the brazilian version of settlers of Catan, and suspected the dice
that came with the game suffered of really shoddy brazilian quality
manufacturing, because the game didn't was nowhere near fun as I had heard of
it on Internet, with extremely frequent long rounds of nothing happening.

I tested the dice, by hand. And indeed, the dice, despite being a pair and
thus theoretically greatly favoring 7, instead had a bias towards 2, 3, 11,
12.

Since most players put their important stuff on nunbers closer to 7, it became
obvious why the game was sucking. (The match that made me go check the dice,
had 4 turns in a row where even summing all players resources we still didn't
had enough to build roads and do basic actions!!!)

~~~
vonzeppelin
My friends and I have played a million hours of Settlers of Catan but once we
used machined dice from a casino in Vegas and they absolutely revolted,
refusing to play until we replaced the dice. The robber, 7, was being rolled
so many times and they weren't used to it all. They hated it! It almost seems
like the imperfect dice are intentional.

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kalleboo
Direct link to the original with all the juicy data:
[http://www.markfickett.com/stuff/artPage.php?id=389](http://www.markfickett.com/stuff/artPage.php?id=389)

Includes gems such as "I also tried rolling pigs from Pass the Pigs, but they
did not roll sufficiently"

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todd8
Dice can be unfair in a wide number of ways. Here are a few.

They can be weighted so that one face lands down more than others. One
approach to detecting such weighted dice is to burn them looking for metal
residue in the ashes. Cheaters got around that by simply hollowing out parts
of the dice to unbalance them. Both metal weighted and hollowed out dice can
be detected by dropping them in a glass of water and watching to see if they
tend to turn while floating or falling through the water. Cheaters got around
that common test by using mercury weighting with a chamber in the center where
the mercury resides when the dice is to act fair and a connected chamber near
the edge where the mercury is knocked to by the cheater rapping the dice on
the table before a roll. Now, casino dice are clear to make it easier to
detect weighted dice, but of course cheaters still try to put bits of heavy
metal under the painted dots!

Dice can also me made in a fashion so that the tend to roll off some sides
more easily. This, naturally, is more of a problem with dice that have beveled
corners. Casino dice have nice sharp edges.

Instead of being rounded, some sides of the dice can be cupped, causing a
suction cup effect that causes the dice to roll less easily off of one side.

Dice can be manipulated by narrowing them in one or more dimensions. Non-cubic
dice may have just slightly smaller faces on some numbers or slightly slanted
faces, making them roll in a non-fair fashion.

In the army, dice games are often played on the surface of a bed's blanket.
Cheater put a small little burr below the surface in one of the dots to make
it catch on the blanket fabric.

Finally, there are "joke store" dice with bad numbering, for example no single
dot face.

A favorite of mine are a set of 4 dice with obviously strangely number sides.
Bradley Efron [1] invented a way of numbering four dice so that no matter
which die is chosen by your opponent first, there is a die that you can pick
from the remaining three that will roll a higher value that your opponent two-
thirds of the time!!!

[1]
[https://en.wikipedia.org/wiki/Bradley_Efron](https://en.wikipedia.org/wiki/Bradley_Efron)

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dividuum
Reminds me of the great Dice-O-Matic by GamesByEmail:
[http://gamesbyemail.com/news/diceomatic](http://gamesbyemail.com/news/diceomatic)

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ARothfusz
I've been told that the fewer times your die bounces, the more random the roll
will be. The reason given was that each time it bounces, you give an
opportunity for a slightly heavier side to roll towards the bottom. Obviously
you should be wary if someone's roll doesn't bounce at all -- they are likely
manipulating the throw (make them use a dice cup!). But a too-bouncy table can
cheat you too by favoring the heavier side of the die.

So, your dice may be trying to kill you, but they're not working alone. Blame
the table too!

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ourmandave
Here's someone testing d6s to see if 1's really do come up more often. He used
student labor instead of a machine.

[http://www.dakkadakka.com/wiki/en/That%27s_How_I_Roll_-
_A_Sc...](http://www.dakkadakka.com/wiki/en/That%27s_How_I_Roll_-
_A_Scientific_Analysis_of_Dice)

~~~
awi
That "study" claims rolling a 1 has a probability of 29% for the tested dice.
I saw it when it was published and was very sceptical, and so where others.
One guy decided to roll 1000 D6 and count the number of 1's, he got 169.
Pretty close to the expected number and far off 290 as the study would
predict.

I calculated that the chance of rolling 169 or less ones out of 1000 rolls,
assuming the chance rolling a 1 is 29% is 0.0000000000000000000459 (far far
below the p-value needed to prove a new particle btw).

To quote the guy rolling the 1000 dice:

"Basically, I'm forced to assume that there is three options

A) Said students decided 'bugger that old idiot telling us to roll a bunch of
dice', made up some numbers and went for a beer B) He can't do data processing
worth poop C) He is outright lying

Take your pick, but it's one of those three."

Complete discussion thread is here:
[http://warhammer.org.uk/phpBB/viewtopic.php?f=3&t=31419](http://warhammer.org.uk/phpBB/viewtopic.php?f=3&t=31419)

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cthulhujr
>If you're rolling it and getting lots of 4s and 3s, it's because your die is
messed up.

Video quickly went from science to BS. Random results and even distribution
are not the same.

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retro64
And this is the #1 reason I rejected D&D 3rd edition when it came out: higher
was always better. (okay, not really)

In truth though, in previous editions it was not consistent, so you never knew
if higher or lower would be required of a particular die, and sometimes it
would be at the DM’s discretion.

Your "lucky" (cleverly microwaved) dice were no match against the true genius
baked into 1st edition.

~~~
r_smart
Huh, that's an interesting take on things. I liked the newer versions because
most gamers I've played with (and on the internet) seem to struggle with how
to use THAC0. So being able to tell them roll as high as possible was nice,
and help speed things along more (except people who suck at THAC0 also suck at
keeping track of modifiers). But I also bought some Game Science dice, so
there's that.

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rootlocus
This is a very interesting experiment, but I was wondering if the dice rolling
was sufficiently natural / random. The can automatically rotates at 90
degrees, but when it comes back up, the dice seems to spin a lot on the
vertical axis, showing bias towards the upper half of the faces. However, I
did not see what effect the first half of the motion had on the dice.

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douche
I'll be that guy... [https://xkcd.com/221/](https://xkcd.com/221/)

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1337biz
Hickory dickory dock.

The Diceman is never fair.

