The Forge Forums Readonly Archives
The live Forge Forums

Articles

Reviews
Welcome,
Guest
. Please
login
or
register
.
October 14, 2019, 03:34:49 PM
1 Hour
1 Day
1 Week
1 Month
Forever
Login with username, password and session length
Forum changes:
Editing of posts has been turned off until further notice.
Search:
Advanced search
275647
Posts in
27717
Topics by
4285
Members Latest Member:

Jason DAngelo
Most online today:
140
 most online ever:
429
(November 03, 2007, 04:35:43 AM)
The Forge Archives
Inactive Forums
The Riddle of Steel
Math Help
Pages:
1
[
2
]
« previous
next »
Author
Topic: Math Help (Read 5364 times)
Jaif
Member
Posts: 327
Math Help
«
Reply #15 on:
August 26, 2002, 11:38:32 AM »
Quote
but what is meant by C(D N)?
The
C
ombination of D events taken N at a time.
Let's say you want to figure out the probability that you get 2 successes (exactly). Step 1 is to figure out the odds of the first & second die both being successes, and the remainder failures. Step 2 is realizing that the chance of the first and second die being successes is the same as the 3rd and 4th, the 2nd and 5th, or any other combination of 2 dice out of the 5. Then you find the number of combinations, and multiply the probability by that number.
In a math text book, the "(D N)" part would be vertical, but I lack the skills to make that happen in the messages. :)
Now, a mistake I found. I switched the "t1" and "11t" parts, so the forumula should be:
C(D N) * ((11T)/10)^N * ((T1)/10)^(DN)
Again, I think. I made an elementary spreadsheet to check this out, and the numbers are looking good, but this is a stab at something I did ages ago, so please check.
Jeff
Logged
Mike Holmes
Acts of Evil Playtesters
Member
Posts: 10459
Math Help
«
Reply #16 on:
August 26, 2002, 11:46:25 AM »
Hey, Shane, as you can see from the math in Jeff's post (and my own stupidity), it gets a bit complicated. Why are you interested, exactly? Is it just curiosity, or do you have some practical application that you are trying to apply? If the latter, if you let us know what it was about, we might be better able to help you with whaterver it is.
Mike
Logged
Member of
Indie Netgaming
Get your indie game fix online.
Mike Holmes
Acts of Evil Playtesters
Member
Posts: 10459
Math Help
«
Reply #17 on:
August 26, 2002, 12:02:44 PM »
Quote from: Jaif
Quote
but what is meant by C(D N)?
Ah, I get it now. What I was missing, and probably Durgil as well is that you were doing the entire operation for C(D N) and substituting.
C(5 0) = 5!(0!(50)!) = 1
C(5 1) = 5!(1!(51)!) = 5
The full equation with numbers sunbstituted for variables would be:
1
 5!(0!(50)!) * ((5)/10)^0 * ((5)/10)^5  0 successes
 5!(1!(51)!) * ((5)/10)^1 * ((5)/10)^4  1 success
which evaluates exactly as he has it. Once again, Jeff's right on it.
Mike
Logged
Member of
Indie Netgaming
Get your indie game fix online.
ShaneNINE
Member
Posts: 74
Math Help
«
Reply #18 on:
August 26, 2002, 12:45:08 PM »
Quote from: Mike Holmes
Hey, Shane, as you can see from the math in Jeff's post (and my own stupidity), it gets a bit complicated. Why are you interested, exactly? Is it just curiosity, or do you have some practical application that you are trying to apply? If the latter, if you let us know what it was about, we might be better able to help you with whaterver it is.
1. Simple curiosity. I've always gotten into the probability and statistics and such of every RPG I've ever owned. Sort of a side hobby. TROS (with Exalted) is my first diepool game and the mechanics are alien to me. I just want to get a handle on the probability and the math behind it.
2. I want to plug a formula into Excel where I can change the TN, the number of dice, and the number of required successes and see what the base percent chance of getting the required successes is.
Logged
::: Shane
Durgil
Member
Posts: 306
Math Help
«
Reply #19 on:
August 26, 2002, 12:45:42 PM »
Check out what I found on Excel a little earlier today:
=BINOMDIST(N,D,(11T/10),FALSE)
Now, if I wanted to find the chance of getting at least 3 successes with a TN of 6 and throwing 5 dice, I would add up the chances of 0, 1, and 2 successes, as found by the above formula, and subtract that from 1?
1BINOMDIST(0,5,(116)/10,FALSE)BINOMDIST(1,5,(116)/10,FALSE)BINOMDIST(2,5,(116)/10,FALSE) =
0.5
Logged
Tony Hamilton
Durgil
Member
Posts: 306
Math Help
«
Reply #20 on:
August 26, 2002, 12:57:09 PM »
Quote from: Mike Holmes
Hey, Shane, as you can see from the math in Jeff's post (and my own stupidity), it gets a bit complicated. Why are you interested, exactly? Is it just curiosity, or do you have some practical application that you are trying to apply? If the latter, if you let us know what it was about, we might be better able to help you with whaterver it is.
Mike
Knowing exactly how the math works behind the game makes it much easier to create House Rules for things that the author didn't include, possibly change an already present rule to better fit your own tastes or campaign, or just improve your ability to Game Master by properly awarding bonuses or penalties during play without throwing off the balance of the game.
For example, is it better to change the number of dice or change the target number? By knowing how the chance for successes and blunders changes by changing those numbers, you will become a better GM IMHO.
Logged
Tony Hamilton
Mike Holmes
Acts of Evil Playtesters
Member
Posts: 10459
Math Help
«
Reply #21 on:
August 26, 2002, 01:54:49 PM »
Good point Tony.
There is another, pretty obvious technique that you can use when you don't know the math off the top of your head, and you have a spreadsheet. I call it the brute force method. Simply use the RAND function (with ROUNDUP or RANDBETWEEN if you have it) an have the machine count the dice that come up this way or that (using other stat functions like Countif, etc). Can be easier in the short run for coming up with approximations on such things as house rules. Just do a few thousand iterations, and you'll get the idea of where a rule is headed quickly.
Mike
Logged
Member of
Indie Netgaming
Get your indie game fix online.
Durgil
Member
Posts: 306
Math Help
«
Reply #22 on:
August 27, 2002, 04:12:34 AM »
Quote from: Mike Holmes
...use the RAND function (with ROUNDUP or RANDBETWEEN if you have it) an have the machine count the dice that come up this way or that (using other stat functions like Countif, etc). Can be easier in the short run for coming up with approximations on such things as house rules. Just do a few thousand iterations, and you'll get the idea of where a rule is headed quickly.
That's an excellant idea! I've never thought about doing that before, Thanks.
Logged
Tony Hamilton
Durgil
Member
Posts: 306
Math Help
«
Reply #23 on:
September 03, 2002, 09:10:40 AM »
Hi all, if anyone is interested, I've created an Excel Workbook that computes the odds, on one page, of getting a specific number of successes, and, on the second page, finds the probability of getting at least a certain number of successes or more. This is done for pools of tensided dice from 1 to 20 and for target numbers up to 20, and also shows the odds of rolling a botch or fumble. The sheets are protected so that only the target number may be changed, but I didn't use a password to protect them with so if you want to change anything, go right ahead. If anyone's interested, then just send me a short email to the address below, and I'll attach the workbook to the reply.
Logged
Tony Hamilton
Thirsty Viking
Member
Posts: 238
math and multiple d10
«
Reply #24 on:
September 06, 2002, 02:57:16 PM »
As i understand it, you want the average number of succes given a #d and a TN?
ok first use the earlier formulas for
x = the % chance of sucess on 1 die
x = (11tn) /10 when tn < 11
or (21tn)/100 when 10 < tn < 21
or (31tn/1000 when 20 < tn < 31 For the ALWAYS A CHANCE people
y = # of dice rolled
x * y = Average number of success at TN for y dice
if you put these into a spread sheet, you will then have the comparative effects of changing either the TN or the # of dice. in terms of the AVERAGE # success per role
hope this answers what you were looking for.
send me your email, and i'll send you my works spread sheet for this.
Code:
TN
d10
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
3.0
2.7
2.4
2.1
1.8
1.5
1.2
0.9
0.6
0.3
4.0
3.6
3.2
2.8
2.4
2.0
1.6
1.2
0.8
0.4
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
6.0
5.4
4.8
4.2
3.6
3.0
2.4
1.8
1.2
0.6
7.0
6.3
5.6
4.9
4.2
3.5
2.8
2.1
1.4
0.7
8.0
7.2
6.4
5.6
4.8
4.0
3.2
2.4
1.6
0.8
9.0
8.1
7.2
6.3
5.4
4.5
3.6
2.7
1.8
0.9
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
A warning, players will expect a little consistency, make decisions on trends, not current situation.... lie about opponents die roles not how a situation is handled when the story demands it.
Logged
Nil_Spartan@I_Hate_Hotmail_Spam.Com
If you care to reply, the needed change
should be obvious.
John Doerter Nashville TN
Pages:
1
[
2
]
« previous
next »
Jump to:
Please select a destination:

Welcome to the Archives

=> Welcome to the Archives

General Forge Forums

=> First Thoughts
=> Playtesting
=> Endeavor
=> Actual Play
=> Publishing
=> Connections
=> Conventions
=> Site Discussion

Archive

=> RPG Theory
=> GNS Model Discussion
=> Indie Game Design

Independent Game Forums

=> Adept Press
=> Arkenstone Publishing
=> Beyond the Wire Productions
=> Black and Green Games
=> Bully Pulpit Games
=> Dark Omen Games
=> Dog Eared Designs
=> Eric J. Boyd Designs
=> Errant Knight Games
=> Galileo Games
=> glyphpress
=> Green Fairy Games
=> Half Meme Press
=> Incarnadine Press
=> lumpley games
=> Muse of Fire Games
=> ndp design
=> Night Sky Games
=> one.seven design
=> Robert Bohl Games
=> Stone Baby Games
=> These Are Our Games
=> Twisted Confessions
=> Universalis
=> Wild Hunt Studios

Inactive Forums

=> My Life With Master Playtest
=> Adamant Entertainment
=> Bob Goat Press
=> Burning Wheel
=> Cartoon Action Hour
=> Chimera Creative
=> CRN Games
=> Destroy All Games
=> Evilhat Productions
=> HeroQuest
=> Key 20 Publishing
=> MementoMori Theatricks
=> Mystic Ages Online
=> Orbit
=> Scattershot
=> Seraphim Guard
=> Wicked Press
=> Review Discussion
=> XIG Games
=> SimplePhrase Press
=> The Riddle of Steel
=> Random Order Creations
=> Forge Birthday Forum