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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9
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2answers
1k views

What is the statistical difference, if there is one, between rolling d20 twice (action and bonus action) and rolling once with advantage?

In our 5e campaign, I'm playing an 8th-level Rogue (Arcane Trickster) with the Crossbow Expert feat, which (among other things) means I can shoot twice in one turn: once as a bonus action and once as ...
5
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2answers
449 views
+100

How to calculate the likelihood of success for increasing DC

How would I go about calculating the odds of success someone has, given N total tries at a skill check, a skill modifier of M, ...
2
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3answers
178 views

What are the probabilities of rolling doubles in a pool of d6s?

I am thinking of designing a ttrpg, and as a dice rolling system I was thinking of a system where players roll a pool of d6s. Any roll that results in multiples of the same number is a success, and is ...
7
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3answers
931 views

Is Deadly Aim worth it?

Deadly Aim is very similar to Power Attack in PF1, in that it reduces your chance to hit in exchange for some extra damage. In PF2 however the enemies' AC increases together with your attacks, so -2 ...
7
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2answers
342 views

Adding the probabilities of multiple outcomes in AnyDice

I don't know if this has been answered before. I've certainly looked for similar questions for a few hours, but even if I find similar ones, I still cannot work out the answer to this problem. In a ...
2
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1answer
176 views

Ability increase for extra HD not calculated correctly under the Lycanthrope entry in the Monster Manual?

In the SRD it states: https://www.d20srd.org/srd/improvingMonsters.htm#abilityScoreImprovement Ability Score Improvement Treat monster Hit Dice the same as character level for determining ability ...
6
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3answers
2k views

Analyzing a homebrew casting mechanism

Background I'm a DM and setting builder working on creating a new homebrew set of classes/subclasses for my world. The basic in-universe mechanic is that the caster is channeling their energy through ...
4
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2answers
521 views

What is the average damage of a Potion of Poison?

The potion of poison (DMG p.188) is an uncommon magic item that deals poison damage over time to anyone who drinks it. However, the way it deals damage is rather complicated, with multiple saves and ...
0
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2answers
170 views

Dice probability in variable pools with receding difficulty [closed]

Can't quite wrap my head around how to go about this (outside of brute forcing it with manual calculations, which isn't ideal given variable difficulties and variable numbers of dice) so I figured I'd ...
13
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2answers
544 views

Are There Alternatives to Dice Discussed in any D&D Literature?

On a family camping trip we found that we had left our dice on the kitchen table at home, and we have a family tradition of not using phones or other devices while camping. And yet D&D must be ...
5
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3answers
129 views

Anydice: Counting Successes and Rerolling Failures In Dice Pools

I'm trying to model my RPG system in Anydice. The rules are: Roll 3d20. A die that rolls under your stat is a success. If you have advantage, you may reroll a failed die. If you have disadvantage, you ...
16
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2answers
2k views

'Advantage' or 'Disadvantage' on damage rolls

I am looking at creating a few new categories of weapons just to add a bit more reason to spend money on mundane equipment in the early game. Poor, and Masterwork. My initial idea is that poor weapons ...
13
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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,...
5
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3answers
380 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
342 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
124 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
votes
1answer
134 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
289 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
100 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
609 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
92 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
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2answers
78 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
323 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
229 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
116 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
184 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
326 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
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2answers
314 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 ...
5
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2answers
403 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
146 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
167 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
119 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
166 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
78 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
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2answers
282 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
160 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 ...
11
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3answers
1k 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
261 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
354 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
189 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
85 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
766 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
431 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
81 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 ...

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