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275647 Posts in 27717 Topics by 4285 Members Latest Member: - Jason DAngelo Most online today: 62 - most online ever: 565 (October 17, 2020, 02:08:06 PM)
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Author Topic: Dice probabilities question and meta-question  (Read 11260 times)

Posts: 576

« Reply #15 on: August 24, 2006, 08:28:17 AM »

I'm not sure what you are looking for, but to find the average of a die you take the number of sides, divide by two and add 0.5.  So a 1d4 will roll a 2.5 average.
That gets you the median (mean?) value, not the average. For the average, I think one sums the lowest value and highest value, then divides by two.

Suppose a die rolls from 0 to 9? Your method delivers an average of 5.5, when it's actually 4.5.

This first method assumes highest value = number of sides, which is true for a d10 if you consider the 0 a 10, as most games do.  Your method is more broadly correct, as long as each value appears the same number of times.  For any fair die, the mean = median.

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Posts: 407

« Reply #16 on: August 24, 2006, 09:12:08 AM »

2) Does this matter?  Am I going to get anything useful from looking at these distributions?  Should I just go with my gut and have it playtested?

(PS: On the drive home from Gen Con I wrote the complete notes/outline of a game.)

Hi Rob,

To answer question 2: Yes, it matters; in games with dice, dice mechanics affect the shape of play greatly.  However, you probably don't need to know curves and probabilities and all the rest of that, except in very broad terms.  I would suggest you're going about this a little bit backwards:

In the context of your game, find out what effect you want the dice to have, both in terms of possible range and effect and probably outcomes.  Then develope on the mechanic that does that, playtest it to confirm it matches expectations.  Lacerate, rinse, repeat.

Dice mechanics and probability curves are fun (for some people) and useful to know as a tool in your designer's belt, but without the context of the game it's going to be in, it's basically mathamatical wanking.

So... what's your game idea?  (probably best for a new thread, esp. since it seems you've gotten your answer to #1)


I write games. My games don't have much in common with each other, except that I wrote them.

Robert Bohl

Posts: 525

« Reply #17 on: August 24, 2006, 09:42:56 AM »

New thread created.

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Posts: 145

« Reply #18 on: August 25, 2006, 11:21:33 AM »

For odd dice questions, the rpg-create Yahoo group is a great place to ask -- Torben Mogenson, the author of the "Roll" language for expressing dice hangs out there, and often fields questions about dice probabilities.
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