"Probability for Game Designers": kick-butt article

• "When you roll a six-sided die, the chance of rolling a “6” is 1/6 = 16.7%—assuming a fair ‘throw’ and a perfectly manufactured die, of course. This 16.7% is not a guess, nor anything of the like. It is as good as fact*."
  16.7% is not a fact, it is an approximation. There's nothing wrong with using approximations in this context, but not claim you're not doing it! It seems that using ≈ instead of = would be appropriate here, but I'm not sure as it's not in common usage.
• "(1/6)4" should be "(1/6)⁴". Minor editting problem (compared to the other problems.)
• "The gist is, if you flip a coin 1 million times, you’ll expect the heads and tails split to be close to 50%. But don’t expect the NUMBER of heads flips to equal the NUMBER of tails flips — in fact, it’s very likely that they will be off by hundreds or even thousands. Remember, you could have 10,000 less heads than tails and the division would still be very close to 50%/50% (49%/51%, to be exact)."
  Although this could be a typo or rounding, I don't think it is. Most likely the other thought that going from 50% to 49% was a 10,000 difference, and didn't realize it applied again when going from 50% to 51%.
• Regarding seeding a pseudorandom number generator with the time, "But for high-intensity games with tons and tons of random number generations, sometimes that’s not random enough."
  Actually, with a good PRNG, the time is enough. It's always predictable though, if you put enough effort into it. For most games that doesn't matter, since it's easier to use a cheat code or edit a save file. However, if money is involved, or it's an online game that you can't otherwise cheat at, the effort becomes worthwhile, and you need to use a cryptographically secure PRNG—this CSPRNG must be seeded from a CSRNG (not pseudorandom), usually fed network or harddrive timings (software), or thermal noise (hardware), thus supplying your "entropy".

Piratecat said:

Amusing note: this was brought home to me when I was writing Of Sound Mind, and Sagiro pointed out that an average party had something like a 60% chance of someone dying just from climbing down a rope. . .

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Rhamphoryncus said:

Despite the faults, I think the article is still worth reading. Just be aware of what it glosses over.

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Piratecat said:

Man, I love smart people who know what they're talking about. Thanks! Good clarifications - and welcome to the boards.

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Piratecat said:

Man, I love smart people who know what they're talking about. Thanks! Good clarifications - and welcome to the boards.

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Plane Sailing said:

I enjoyed the article, apart from their determination to turn everything into percentages at the earliest possible opportunity, when keeping the fractional numbers would have made their point more clearly. Presumably this is something to do with writing for game writers?

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