Irregular dice and mechanics?

[Penbot 2004]

A few weeks ago I noticed one of my six sided dice was quite irregular. For a few months now I've been buying dice from ebay. There's always someone who's cleaning their closets and will sell some dice cheap. This d6 had a matching d12 and it's irregular too.

In other words, all opposeing sides do not add to 7 or 13. Then, this past saturday, I found i have some d8 that are irregular as well.

I can only imagine that irregular dice would throw a giant kink into dice mechanics! Anyone know any stats or figuers about irregular dice? How much worse are their odds?

I'm gonna put them all up for sale on ebay. lol

[grifflik]

Yes, typically the opposite sides of a six-sided die add up to seven (6 opposite 1, 2 opposite 5, 3 opposite 4). However, if the die still has each number only represented once (only one 1, one 2...one 6), probability is not affected. You would still have the same chance of rolling any given number: 1 out of 6. The same would be true for any die. Despite irregular number placing, so long as each number is represented, probability is not affected. Their odds are no worse or better than dice whose numbers are placed regularly. Now if there were two 1's and no 6 or something like that, probability would be affected, but that doesn't sound like what you have.

[EDIT]
Also - diagonally opposing facings on an eight-sided die typically add up to 9 (8 and 1, 7 and 2, 6 and 3, 5 and 4). I have some cheaper quality dice in my classroom collection that do not do this - instead, diagonally opposing facings add up to 7 (6 and 1, 5 and 2, 4 and 3) with one exception, 7 and 8 (you can thank some of my students for checking this for me). Again, however, despite the irregularity, probability is not affected since all numbers 1-8 are still represented on the die.
[END EDIT]

That said, you might want to check the six-sided dice to see if any are fixed or "loaded" (roll a particular number more often than any other due to weighting modification in the die). When buying used dice in bulk like you have been, there's a chance that you've ended up with some loaded sixers used for craps or such (heck, you can even buy loaded dice at some hobby shops where you typically buy dice...not very sporting).

[Penbot 2004]

griffik wrote:

"However, if the die still has each number only represented once (only one 1, one 2...one 6), probability is not affected."

That is what I assumed. I just thought I would ask you all. There's little chance the d6 in question is loaded. It's just ugly. I've put 12 random die from my collection back on sale on ebay. For 1.99 starting bid and 1.50 shipping. So far there are no takers. But, they are some really ugly dice. lol, l8r