SR Dice curve, How do you model the dice in a Spreadsheet? Options

[Thorguild]

Hi all,

I need to see the probability curve of the dice to wrap my head around the likely results. Does anyone have a number of hits curve generator for different numbers of dice, and edge dice?

If not, does anyone know the way to model the dice in Open Office or Excel?

Thanks,

Thorguild

[ggodo]

Well, without rule of six you divide by three, with rule of six you do math that I'd love to help with but as am currently supposed to be doing other math I cannot.

[Psikerlord]

Its to do with combinations and permutations. You can probably google the formulas ... I used to know how to do it in high school. Alas no longer.

[thorya]

This spread sheet has the probabilities of reaching thresholds. The successes are the yellow cells and the number along the top is the size of the dice pool. For the columns where you cannot score enough successes, we allow someone to roll dice equal to the threshold where only 6's count as successes and that's the first column. The next page is a normal approximation of opposed checks (it's pretty accurate above 4 or 5 dice). There are no graphs in this particular spreadsheet, but feel free to make some.

http://dl.dropbox.com/u/45448342/SR%20probability.xlsx

edit:
You can check any set of opposed rolls by changing the two cells at the top of the second page to be the desired rolls. Positive equals more successes for the first pool. Negative is more successes for the second pool. The difference between the two percentages is the chance of rolling a tie. Also, I have a more complete sheet somewhere. I'll look it up.

[UmaroVI]

Obviously, the average successes will be 1/3rd the number of dice you roll. A handy rule of thumb:

You are about 65% likely to roll within (square root of twice the number of dice)/3 of the average, 95% likely to roll within twice that, and 99% likely to roll within 3 times that. This is more accurate for larger dice pools. So, for example, rolling 15 dice, you'll average 5 hits, and you are around 65% likely to get between 3 and 7 hits. This is because twice 15 is 30, root of that is about 5.5, a third of that is a bit less than 2. So if you are hoping for 8 or more hits, you know your odds are about 18% or so (35% likely to not get 3-7 hits, half the time less, half the time more).

For opposed tests, the average net hits will be of course 1/3 the difference, and for the odds of getting within however many net hits of the average, use the above but use the total number of dice (not the difference), interpreting negative as the person with the lower dicepool winning.

Of course you can make a spreadsheet, but this is a useful way of eyeballing it.

[Ryu]

I suggest Feshy´s diceroller with statistics function for the numbers. Now where is the sheet for opposed tests...

[Thorguild]

Ryu,

That was EXACTLY what I was looking for.

Thank you