Sunday, February 8, 2009

Sharp-Edged Dice

Over on my gaming blog, I wrote a post on how to test for balanced dice (including any common polyhedral dice used in role-playing games, such as 4, 6, 8, 12, and 20-sided dice). Basically it's an application of Pearson's chi-squared test, and I computed a rejection cutoff value for the SSE (sum-squared error) at a 5% significance level, if you're rolling the die in question 5 times per side. I hadn't seen that specifically presented anywhere else, and I really wanted to see it in a simplified format. I won't repeat it here, but it's over in my gaming blog at the link below:

As a follow-up to that, I tried to do a little research on what game manufacturers do for quality assurance on their dice. While I didn't find that specific information, I did find something that absolutely warmed and delighted my heart. It's the long-time owner of the dice-company Gamescience, "Colonel" Lou Zocchi, engaging in a 20-minute rant about how crappy his competitors' dice are, because they engage in a sand-blasting process that rounds off all the edges of their dice in an irregular fashion, and therefore generates slightly incorrect probability distributions. (As an aside, this actually does match my own independent test of his style of dice he produced.)

Lou's retiring this year and selling the company, but he's still got the fire, and I'll give him an official MadMath salute for his rant on dice probabilities. Watch it here:

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