Linear vs curved dice mechanics

[makke]

The point is that Gurps uses a mechanic that is really difficult to build with flat distributions: A small bonus is better the nearer to an effective skill of 10 you are (=> increasing 10 to 11 is a much bigger deal than increasing 4 to 5).

You could of course model that with a d100 but you would have to use a table for that ... which greatly decreases the speed of the game.

I do think that this mechanic has some merit. Someone who always hits right on the target with his pistol won't need a laser pointer but I as a rather mediocre shot would greatly profit by one. (only one of billions of possible silly examples :) )

@Why is a gauss distribution interesting for simulating realistic results:
A lot of stuff in nature is distributed that way - doesn't mean it's a close fit for everything, tho. But nonetheless if you want to approximate everything with only one distribution the gaussion one is probably your best bet.

[Irish Wolf]

Originally Posted by makke

You could of course model that with a d100 but you would have to use a table for that ... which greatly decreases the speed of the game.

You also need either a really big table, or one with bumpers around the edge like a pool table -those d100s roll forever.

[sir_pudding]

Originally Posted by Irish Wolf

You also need either a really big table, or one with bumpers around the edge like a pool table -those d100s roll forever.

Or you could just be a sane person and use two ten-sided dice for 1d100. :)

[Nymdok]

Keep in mind that Quick Contests can be resolved with a flat distribution, if you know the probabilities.

http://forums.sjgames.com/showthread.php?t=23532

So success rolls and Quick contests CAN be done just find with flat distros as can reaction rolls.

The reason most people dont is not because the system cant handle it, its just not set up for it. Translating everything for 3d6 to % is a pain.

d6 are abundant and cheap. Using only 3 of them keeps some randomness in the roll, but lets you know that your going to be rolling close to the center.

As to using 10d10 for resolution, I dont know if you mean 10 dice added ala 3d6 or each being a digit in a large number but either way, its grotesque over kill.

Remember, the more dice you roll, the higher the peak gets in the midddle and the lower and flatter the ends get. The odds of you getting a central roll gets higher and higher, which is nice for reliability, but just isnt much fun for gaming. If you roll so many dice that there is little variance at all, why roll? Why not just take the expectation value?

Finally, the only beef that I have with the curve vs flat is that modifiers have different meaning depending on where your at on the curve. Have a skill of 10? then +1 gets you a 12% bonus. Have a skill of 13? It only gets you about 7%.

I know that plenty of people like the curve for EXACTLY this reason, but it can be problematic.

For example, say I wanted to assign a 5% positive modifier.

To the Guy with skill 10, I cant! The lowest increment of bonus I can give him is either none at all or 12.5%. Looking at the other side of the curve, at skill 15, is the last place I can give a +1 bonus and thats only worth about 3%. In other words, the only place I can give a +5% is to skill 14. This is just as difficult with a +20%.

Nymdok

[sir_pudding]

Originally Posted by Nymdok

Keep in mind that Quick Contests can be resolved with a flat distribution, if you know the probabilities.

Understanding probability isn't a common feature of game-writers or gamers, IME.

[Rabiddave]

I like how the 3d6 bell-curve works for skills because it seems to line up better with the way learning works in RL better than a flat distribution...

Initial progress is tentative, and then as you reach a general level of competency you start to make real leaps. Then, as you attempt to reach more advanced levels of mastery progress slows back down for the same investment of time. Intuitively, this seems to be a much better model of the learning process.

[Joseph Paul]

Re: learning curves - You can do that in a D100 game also. It has more to do with how you grant skill increases though. One of the BRP derivations did it by allowing a skill increase check after a succesful use. You had to roll higher than your skill to succeed at the check to get the increase. Essentially when you were low skill the odds were good that you would rapidly increase and then start to slack off. Getting to 95% in a skill was tough even with a POW mod to help.

[roguebfl]

Originally Posted by Joseph Paul

Re: learning curves - You can do that in a D100 game also. It has more to do with how you grant skill increases though. One of the BRP derivations did it by allowing a skill increase check after a succesful use. You had to roll higher than your skill to succeed at the check to get the increase. Essentially when you were low skill the odds were good that you would rapidly increase and then start to slack off. Getting to 95% in a skill was tough even with a POW mod to help.

Can, but it not easy, it not a 'natural fit' and actully requires the GM to have a working knowledge of normal-like curves

[whswhs]

Originally Posted by roguebfl

Can, but it not easy, it not a 'natural fit' and actully requires the GM to have a working knowledge of normal-like curves

Actually, that's not true. Consider a very simple rule: Before you can try to learn from experience, you have to succeed in using the skill (roll below); when you try to learn from experience, you have to roll higher than the skill. That's easily understood by people who don't do probabilities. If you are comfortable with math, you can work out that at 1% skill your chance of learning is 1%x99% = 0.99%; at 10% it's 10%x90% = 9.00%; at 50% it's 50%x50% = 25%; and so on up to 99% is 99%x1% = 0.99%.

Bill

[Rocket Man]

Originally Posted by Nymdok

For example, say I wanted to assign a 5% positive modifier.

To the Guy with skill 10, I cant! The lowest increment of bonus I can give him is either none at all or 12.5%. Looking at the other side of the curve, at skill 15, is the last place I can give a +1 bonus and thats only worth about 3%. In other words, the only place I can give a +5% is to skill 14. This is just as difficult with a +20%.

Nymdok

To each their own, but I've never been in a situation where I wanted to assign a percentage modifier. I always think in terms of incremental ones ... and I base it on the situation at hand rather than "What bonuses/penalties will give this character X chance of success?"

Granted, in a "curved system," incremental modifiers will have a varying impact depending on your skill level, as already discussed. But I think that's a good thing. I cannot readily conceive of any real-life situation where adding a new factor would add 5 percent to the success chances for everyone attempting it, regardless of skill.

For the guy with skill 10, even a little help makes a big difference. For the guy with skill 18, the help is almost redundant, except in very difficult circumstances. To my mind, that's as it should be.

(The reverse is true as well, of course. A small problem presents a huge difficulty to skill 10, but is almost unnoticed by skill 18. Again, that seems to square with my own observations.)