Monday, February 20, 2012

Testing Dice Fairness

At my game yesterday, one of my players complained about her terrible dice rolls.  She seemed convinced that they were magically biased against her.  She's a statistician so I suggested she determine empirically whether her dice were likely to be biased by rolling them a lot and then use that to determine the likelihood of their bias.  It's a classic probability problem.  Needless to say she didn't, but it got me thinking.  Given how superstitious gamers are about their dice such a test might actually be interesting to do.

The only people I've seen who seem devoted to dice innovation is a company called Game Science.  I haven't used their dice though.  I think I might buy a set, test them, and compare them to my existing dice.


  1. I have seen docos where vegas dice makers test the fairness of d6s. It involves spinning them on a machine about their axis. Would be hard to test a d20 this way. Lastly, humans don't random grasp random very well. We like to see patterms.

  2. Game science dice are super cool, I have several sets (and handed out d20's as gifts to my group one year) we call them our "fair dice". I understand the concept as to why they are more fair (not egg shape and sharp corners) however I have never tested them (but the stack-up demo is pretty telling in the GS you tube vids) I like the fact they don't roll off the table much more than anything.

    RE Casino dice- I got some (cool colors and they are casino dice!) but the edges are incredibly sharp edged, and in the short stack of 10 or so dice they look extremely uniform (but I am pretty sure they hold the dimensions to the tenths so I wouldn't be able to see or feel the difference anyway). As for the fairness, I was playing a one shot basic dnd game and brought them out (3d6 in order baby!), well after rolling 12 PC's in a row (72 3d6 rolls) with scores ranging from 9-12 I put them away :)

    This blog is sweet, I can't wait to read more, I am an engineer and deal with statistics a fair amount at work (Cpk's and SPC type stuff) so I look forward to reading more!

  3. One of my players decided to test my dice; needless to say they were determined to be fair, but I continued to apparently roll much better than average against the players, or so it seemed to them.