Testing for fair dice

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Rawle Nyanzi
Worthy Tortoise
Posts: 35
Joined: Sun Jun 16, 2013 4:35 pm

Testing for fair dice

Post by Rawle Nyanzi »

While OVA isn't a high-stakes casino game, most players want fair dice.

However, how do you know a die is fair?

Simple; you roll it enough times and see if you get each number roughly equally. But it's still random, so some numbers will turn up more than others.

That's where this Excel file, courtesy of the Giant Battling Robots blog, comes in handy.

Roll your die at least 30 times (do more rolls for more accurate results), then plug the results into the bright green cells on the table's left side. Do not mess with any other part of the spreadsheet. Afterward, look near the bottom of the chart for the "p-value." You will see a message next to it telling you if the die is fair or not.

Even better, the spreadsheet works for dice all the way up to d20.

(If you want to know why rolling a die dozens of times gives you every side in roughly equal measure, look up the Law of Large Numbers. It's quite fascinating.)
Ayleron
Shelled Plebeian
Posts: 14
Joined: Tue Jun 18, 2013 12:30 am

Re: Testing for fair dice

Post by Ayleron »

This may be just because I grew up in Vegas but when we want really fair d6s we just buy casino dice. 8)
Rawle Nyanzi
Worthy Tortoise
Posts: 35
Joined: Sun Jun 16, 2013 4:35 pm

Re: Testing for fair dice

Post by Rawle Nyanzi »

Ayleron wrote:This may be just because I grew up in Vegas but when we want really fair d6s we just buy casino dice. 8)
Nothing wrong with that solution.
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