Questions tagged [statistics]

Statistics deals with the mathematics of probability-based games. This tag should be used for questions about tabletop game mathematics that relate to mechanics rather than game elements such as skills or attributes, and have relevance to RPGs in particular.

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13
votes
5answers
2k views

When performing a group check, is it better to have an even number of creatures?

The rules for group checks say: To make a group ability check, everyone in the group makes the ability check. If at least half the group succeeds, the whole group succeeds. So, for groups of 1 and 2,...
4
votes
3answers
319 views

what are the issues with rolling initiative every round, looking for mechanical reasons rather then opinion [closed]

A friend of mine has mentioned he is thinking of trialing rolling initiative at the start of every round in combat, vs 1 roll at the start of combat for his table. This sounds like a really bad idea ...
3
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2answers
312 views

How many rounds is persistent damage expected to last?

If you do not spend any actions to deal with it, persistent damage ends if you succeed on a DC 15 flat check. What is the expected duration? (as calculated from the chance of ending it)
15
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5answers
1k views

Struggling with rolling for stats probability calculation

I tried finding a specific statistic calculator, even tried playing with anydice.com, with no success. My friends love to roll dice, but we also want the same playing field when starting a campaign, ...
4
votes
2answers
85 views

How do Hard or Extreme rolls vs increasing penalty dice affect the odds of success or failure?

In Call of Cthulhu 7th edition, rolls are made using percentile dice (one standard d10 and one 10s d10). A roll is considered successful if it is less than or equal to a given number for a stat or ...
9
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1answer
123 views

What is the Combat Drill's mean damage and self-heat when its extra damage is triggered?

The Combat Drill weapon in Lancer, located on page 155 of the free version, has an unusual (at least within Lancer's system) damage-determination property that has stymied my attempts to calculate its ...
3
votes
2answers
271 views

Is it possible to make this die probability work?

My best friend and I are doing a thing for a d&d game that involves potentially destroying the universe. This event will occur rarely, but we want to make it show up randomly (because it’s a ...
6
votes
1answer
89 views

How can I calculate expected Stunt Points per attack when FIRST dropping a d6?

I’m trying to determine what the math is if you use the AGE STUNT system, but first roll Xd6 and choose the 2 that you want to keep. Note, the STUNT Die would be rolled at the same time as the Xd6 and ...
22
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2answers
2k views

Roll Xd6, keeping highest value and adding +1 for each duplicate of that value?

I'm making a card/dice game and I'm trying to set something up on Anydice to compare the odds of the dice rolls, but I'm having some trouble wrapping my mind around some of the language Anydice uses. ...
1
vote
3answers
429 views

Statistically, when is wielding a Large weapon worth it for a Medium-sized character?

In D&D 5e, according to p. 278 of the Dungeon Master's Guide, if a Medium-sized character uses a Large weapon, its damage dice are doubled, but it causes them to suffer disadvantage on their ...
12
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4answers
4k views

Is this Homebrew Advantage rule broken?

I know about this suggestion. Mine is an even further extension of that, and I'm asking about whether there are any further issues and whether I've fixed Lucky. I find the way 5e handles multiple ...
4
votes
1answer
82 views

What is the probability distribution for CthulhuTech rolls?

I've recently learnt about CthulhuTech, which has a unique dice pool system: CthulhuTech uses a proprietary game system known as "Framewerk" that focuses on a dice pool system. An unusual ...
3
votes
1answer
59 views

How to calculate the chances of reaching a certain success level prior to failed channeling?

In Warhammer 4e casters can use channeling in order to gain success level prior to casting a spell. Success levels are essentially for every 10 you exceed the skill number you gain a success level and ...
4
votes
1answer
296 views

Modeling a system where you roll Xd20 and take highest, plus the second highest if the first one is a critical, etc

I'm making my own combat/task resolution system (loosely based the advantage mechanic from D&D 5e). In this system a roll with "advantage" is resolved as follows: Roll Xd20 and take ...
3
votes
3answers
204 views

how to calculate the odds of 5d6 higher than 1d10?

In anydice or troll, how can we calculate the odds of rolling 5d6 and counting the successes against 1d10? Successes are every result in each six-sided die equal or higher than the d10 result. This ...
2
votes
1answer
107 views

Calculating Modified V5 Dice Probabilities with AnyDice

My game uses 5th edition rules with a house rule where 1s subtract successes and 10s count as two successes. 2s through 5s count as no successes and 6s through 9s count as single successes as normal. ...
6
votes
1answer
166 views

How to count the number of successes in a very large dice pool more easily?

What is a good way to roll a large number of dice and count how many of them "succeed" (i.e. meet or exceed a set target number)? I'm playing a game called Aberrant that uses the Storyteller ...
6
votes
2answers
313 views

How can I determine the rolling curve of this roll under system?

The system The system relies on Traits and Skills (which both range from 0 to 6). Players rolls a number of d6 equal to the Skill they're using. Any die result equal or under the related Trait ...
6
votes
2answers
197 views

Does increasing the dice pool make messy criticals more likely?

I just read the mechanics for dice rolling in Vampire: the Masquerade 5th edition and something is bothering me. It seems to me that the larger your dicepool is, the more likely it is to get a messy ...
4
votes
2answers
340 views

How would optional re-rolling of all hit dice on leveling up affect average hp?

I am considering a homebrew rule that would give players the option on leveling up to re-roll all of their hit dice (excluding their first level) instead of only rolling their new hit die when ...
3
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1answer
134 views

What is the chance of being hit?

As a companion to this question, what is the expected chance of being hit by an average monster of your level?
4
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1answer
116 views

What is the expected hit chance?

(inspired by this answer) A cursory look thru the Bestiary has shown values ranging from 12 to 19 (plus level). Did anyone collect the data, or has seen any guidelines from the creators?
1
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0answers
115 views

Is the dice system too generous for my rpg? [closed]

I'm writing my paper RPG that sets up in a modern day world, with elite soldiers facing several horrific situations. I wanted to create a game system not too complicated, but not too simple and ...
3
votes
1answer
151 views

Disadvantage/adversity dice pool mechanic that knocks dice greater than 1 out of the pool and adds 1s to it

I am working on a dice pool system for skills and actions to be used in a new system. In this system, any rolls of 1 will negatively affect the outcome of resolving an action using a dice pool. In ...
14
votes
3answers
5k views

When aiming to roll for a 50/50, does the die size matter?

I noticed how D&D 5e's Hexblade Warlock subclass feature Armor of Hexes imposes a chance to miss regardless of the attacker's roll. That chance is based on a d6: if it's a 4 or higher it misses, ...
2
votes
1answer
65 views

How to count near duplicates in a mixed pool using AnyDice?

Following on from this question: How to count duplicates in a mixed pool using AnyDice? I'm also interested in the much harder question of using AnyDice to look at how much easier some dice mitigation ...
5
votes
2answers
256 views

How to count duplicates in a mixed pool using AnyDice?

The following question provides a function that answers the question for a single kind of die; How do I count the number of duplicates in anydice? I want to count how many duplicates there are in a ...
3
votes
3answers
149 views

Opposing d6 Pools, # of higher dice

I've read dozens of posts here, and wrestled with with anyDice suggested code, but nothing matches quite what I am looking for. I think it is simple in concept: for opposing dice pools of 1..6d6, I ...
10
votes
2answers
979 views

Dice rolling mechanic where modifiers have a predictable and consistent effect on difficulty

I am looking for a dice rolling mechanic that makes it such that increasing or decreasing a modifier on the roll has a constant multiplier effect on the probability of the outcome. Say you have to ...
7
votes
8answers
2k views

How to handle degrees of success in roll under systems

I'm working on an RPG system that uses 2d6 roll under Skill for resolutions. On paper this system looks really good so far, but I have one major issue: Degrees of Success, especially when it comes to ...
7
votes
1answer
233 views

Is there an easy formula for multiple saving throws?

My issue: I am playing a druid and if I do something like summon 8 wolves I can end up forcing the DM into 8 saving throws each turn. I mitigate this on my end with an app to roll lots of dice, I pre-...
2
votes
2answers
301 views

How to include successful saves when calculating Fireball's average damage?

I want to know how to calculate the average damage of a spell that also deals half damage on a successful save. For this example, I'll be taking the most popular evocation spell, Fireball. As far as ...
5
votes
1answer
174 views

Chances of specific sequence in X amount of dice?

So after fumbling around in AnyDice for awhile, I’m struggling to find a solution. Here’s what I’m looking for: What are the chances of rolling a specific number that matches a specific sequence in ...
2
votes
3answers
77 views

How to make Anydice see if two values are the same among 3 dice and keep them?

Is there a way to calculate/simulate rolling 3d20 and spit the middle one (that is easily done with middle function), or if its value is the same as the high or the low one, spit that one too? Here it ...
7
votes
2answers
711 views

Is it possible to model these probabilities in AnyDice?

I was asked by a pal to help him model a dice mechanic in AnyDice. I must admit I am an absolute neophyte with it, and I offered to solve it using software I'm better versed in. I'd like to be able to ...
26
votes
12answers
5k views

What is the ideal way of emulating a full dice set using a single d20?

Imagine you are trapped in a post-apocalyptic world and only have a single d20 at your disposal, nothing else whatsoever. What is the ideal way of emulating all other common dice types (d4, d6, d8, ...
12
votes
2answers
395 views

How can I ensure my dice roll fairly if they appear to have a bias?

I have purchased several sets of dice from different online retailers. I did some salt-float tests on them recently and I'm concerned a good amount of my d20s are favoring a specific corner (all 3 ...
4
votes
1answer
74 views

How do I graph the chance of success with a range of dice pools against a range of target numbers?

I'm having a hard time coding an anydice script to show what I want. Let me contextualize the mechanic I'm trying to simulate: You roll a POOL of d10 against a TARGET number. If at least one die from ...
3
votes
2answers
114 views

What target numbers would be a certain level of difficulty under this system?

I’m writing a homebrew game system, and I found that I have an action resolution mechanic but not a good system for target numbers (I call them Success Thresholds, or STs, in this game, and from now ...
4
votes
3answers
348 views

Which modifier added to a 1D20 has the closest outcome probability as rolling 2D20 with advantage with no modifier? [closed]

I'm trying to determine the probability of every modifier to a 1D20: 1D20 +1 1D20 +2 1D20 +3 1D20 +4 1D20 +5 vs flat 2D20s with advantage ...
3
votes
1answer
569 views

At what point is a Lifedrinker Warlock's expected damage reduced by Sharpshooter/GWM?

At Level 12, a Pact of the Blade Warlock can take the Lifedrinker Eldritch Invocation, which states the following: When you hit a creature with your pact weapon, the creature takes extra necrotic ...
10
votes
2answers
940 views

What is the formula for Unarmored Movement's bonus?

I'm trying to plug in an equation for a monk's unarmored movement in DiceCloud, so that I don't have to change the bonus value whenever it changes. I had a formula, but lost it. Does anyone know what ...
15
votes
5answers
6k views

A player rolls several 20-sided dice, takes the lowest value, ignores the rest. What is the probability of this value being at least 7?

I'm designing a tabletop game, and I need to figure out how to calculate a few probabilities: Roll 3 20-sided dice, take the highest value. What is the probability of it being 7 or higher? 15 or ...
5
votes
3answers
542 views

How to calculate the probabilities for eliminative dice pools (dice cancelling mechanic) in Neon City Overdrive?

The game Neon City Overdrive uses the following resolution mechanic for checks: create a pool of Action Dice and (possibly) another pool of differently-colored Danger Dice (all d6, generally up to 5 ...
1
vote
2answers
238 views

What is the formula for damage per round?

I'm creating a web app to learn JS that will calculate damage per round but I'm stuck on adding criticals. I have successfully created variables for: diceNumber, diceSides, bonuses, attacksPerRound, ...
6
votes
1answer
607 views

What is the percentage of possibly hitting something that has stacked Blur, Blink, Mirror Image, and Armor of Hexes?

This question is mostly for hypothetical fun because setting all of these up isn't super practical (unless it's a 1-on-1 campaign perhaps?) But with all of these stacking, how likely are you to be ...
4
votes
1answer
192 views

How do I calculate d20 success probability using the Halfling 'lucky' trait with advantage?

Here is a comprehensive DPR calculator, and here is the mathematics behind it. I'm trying to follow along with the equations. At the bottom of the second page are formulas for success probability \$L\...
15
votes
3answers
3k views

What's worse, -2 or disadvantage?

So, I'm building a system that adds an extra level of flavor, with some minor mechanics as an optional side system for a 5e campaign. The basic function is, you collect points, then collect a deficit. ...
3
votes
5answers
182 views

For anydice.com, is there a way to set a total number for three rolls?

I am very, very new to writing code and working on designing a RPG. As part of that, I am trying to do a simulation of three weighted dice rolls, ranging from 1-12 where I set the limit of how much ...
9
votes
3answers
2k views

How do I mathematically find this distribution?

I roll 10d6. I can then reroll any ones or twos. Then, I can reroll any ones. What is the distribution of the number of sixes I will have?

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