LogFAQs > #922883942

OniRonin posted...

There are 8 numbers 17 or higher that can come up on 4 d6's -- 17, 18, 19, 20, 21, 22, 23, 24. 21, 22, 23 are subtracted by 20 to give 1, 2, and 3. 24 is ignored. So you have a 4/23 chance of rolling 17+ on 4 d6's, which is 17.3%, very close to the d20's 15-20% depending on how you do the math.

Let's put this as simple as possible, a d20 gives you 20 possible roles, all having the same 5% chance of occuring, the numbers from 1 to 20.

Rolling 4d6 has 1296 possible outcomes. the two extremes, 1+1+1+1 and 6+6+6+6, both only have a 1/1296 chance of being rolled. Whereas the peak of the bell curve, 14, has 146 ways of it being rolled.

In your 4d6 system, chance to roll a 4 is 0.077%. The chance to roll 14 is 11.27%. Both quite a bit away away from the 5% of a d20.

And yes, systems like yours exist. Some use 3d6 instead of 1d20, to intentionally skew the results in the favour of the average. As they give more power to statistical character bonuses, while depending less on luck.

OniRonin posted...

A 17+ includes 17,18,19,20. Because there are 20 numbers between 1 and 20, that corresponds to an ideal of a 20% chance. Your method gives a 15% chance of a 17+, whereas mine gives a 17.3% chance, so it's actually more accurate than yours.

Are you serious right now? He used 17+ as meaning, 18, 19, 20, that leads to 15%. The way you use the number, a d20 gives a 20% chance. Because that is the entire point of a d20, 20 outcomes that are equally likely to come up.

Also, I am only getting to a 13.13% chance in my calculations for rolling a 17 or higher in your system.
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