Revision that eliminates passive perception

[BeefGood]

I think that the explanation of passive checks in the rulebooks is not good. Below is a proposed revision of the concept. Of the two major schools of thought on passive checks, the No-Roll School and the Non-active/Check “Floor”/Always-On Ability School, I chose the No-Roll School. Accordingly, perhaps the most important feature of this revision is that terms like “passive check” and “passive perception” are gone, and constructions like “he or she has a passive Wisdom(Perception) score of 14” are not used.
This text replaces the Passive Checks section on p. 175 of the PHB. All references to passive checks, etc, in the rulebooks are removed.
What do you think?

<begin>
ABILITY CHECKS WITHOUT DIE ROLLS
Sometimes the DM may wish to resolve an ability check without making or requesting a die roll that would clue the player that something interesting is going on. Such a situation can be addressed by assuming that a roll was made and that the result was the d20 average, 10.5, rounded down to 10 per the game convention. Then add the relevant modifiers to attain an ability check value, the “average roll” value. If the character has advantage on the check, add 5. For disadvantage, subtract 5.
For example, a character walks by a secret door. The DM wishes to determine, without rolling a die and without asking the player to roll, whether the character notices the door. The character is 1st level, has a Wisdom of 15 (Modifier +2), and proficiency in Perception (1st level bonus +2). The character’s “average roll” Wisdom (Perception) check, determined by the DM, is then 10+2+2, or 14. If this a DC 15 secret door, then the character does not notice the door, and the DM says nothing to the player.
The player may later announce an intention to search the wall for secret doors. This situation is resolved as usual: the DM requests a Wisdom(Perception) check, the player rolls a d20 and adds relevant modifiers to form the ability check value, and this value is compared to the DC of the secret door.
The DM may wish to avoid rolling dice when a player requests, or an in-game situation calls for, an inconveniently large number of ability checks. For example, a player announces an intention to search every single flagstone for traps. Rolling dice for each check would bog down the game. The simplest approach to this situation is to use the “average roll” ability check value for every one of the ability checks. This is quick and easy, but makes sense only if there are few real challenges. For example, if only two of the fifteen flagstones searched have traps, then all of the possible outcomes--finding both traps, or finding neither trap, or finding one but not the other (if the traps have different DCs)—are plausible. But if there are many real challenges, such as during a night of arm-wrestling contests at the tavern, then the mathematical improbability of achieving the same ability check value for each challenge becomes increasingly difficult to overlook.
An approach that yields more plausible results uses the Ability Check Success Rate table. Given the difference between the character’s “average roll” ability check and the DC of the challenges, the table provides the percentage of challenges that succeed. For example, the character above (1st Level, Wisdom 15, Proficiency in Perception) walks by ten secret doors. The character’s “average roll” ability check value is, as before, 10+2+2=14. If the DC of the doors is 15, then the difference is -1. According to the table, the character finds about 50% of the doors.

ABILITY CHECK SUCCESS RATE


“Average roll” ability check – DC
Success Rate


7 or more
100%


2 to 6
75%


-3 to 1
50%


-8 to -4
25%


-9 or less
0%



The table is easiest to use when the DCs of the individual challenges are the same, or at least when all the differences are in the same band in the table. The table is most helpful when it doesn’t matter which challenges are overcome. For the night of arm-wrestling contests, if the gold is distributed based on the percentage of contests won, then the table is all that is needed to determine the payout. If it does matter which challenges are overcome, as in the case of ten secret doors, then the DM must devise a method to determine which doors were found.
<end>

EDIT: Found Table formatting button and used it. Much better!

[TrinculoLives]

I mean, it sounds a great deal like Passive skill checks, except that it also includes a mechanic for a nuanced possibility of failure or success for when several passive checks are made in a row: as when a character walks past several secret doors.

Considering that this rarely comes up, I don't see that there is much call for this mechanic's application. And considering that passive checks are themselves intended to simplify the process of making multiple checks, it seems counter-intuitive to modify the system in such a way that grants it greater granularity.

If the DCs are all the same, perhaps the character should not be able to find any. And if the DCs consist of numbers that are both higher and lower than the character's passive check, then the character will find some but not others anyway.


I could be missing something important. Please explain why you think that the passive skill checks in the PHB are not good. Then I will be able to re-evaluate this system in light of your concerns.

Edit: Oh yeah, this system assumes that a PC will always beat DCs of checks that are lower than its passive check, so it only increases the rate of success. Surely this is also "statistically inaccurate" as well.

[Tanarii]

I could be missing something important. Please explain why you think that the passive skill checks in the PHB are not good. Then I will be able to re-evaluate this system in light of your concerns.What you missed is he's trying to eliminate the term 'passive' from passive skill checks, to remove the misconception that passive skill checks are only used for things that are passive on the part of the PC. As opposed to what they are defined by RAW as: "a special kind of ability check that doesn’t involve any die rolls" which "can represent the average result for a task done repeatedly" or "be used when the DM wants to secretly determine whether the characters succeed at something without rolling dice".

[BeefGood]

Here is the math behind the Ability Check Success Rate table. This is just for those who are interested. It’s not intended to go in a rulebook.
Call the normal ability check the Rolled Check or RC.
(1) RC = d20 + modifiers (ability score modifier & proficiency bonus).
An ability check succeeds if the Rolled Check is greater than or equal to the Difficulty Class, so the relevant probability is
(2) P(RC >= DC).
The “average roll” check, or ARC, is 10 + modifiers.
(3) ARC = 10 + modifiers
The quantity in the left-hand column of the Ability Check Success Rate table is the difference between the “average roll” check and the Difficulty Class. Call it Delta:
(4) Delta = ARC – DC. We will use this equation in the rearranged form,
(5) DC = ARC – Delta.
When Delta is positive, the “average roll” check is greater than the DC, and we expect the probability of a successful check to be high. When Delta is negative, the “average roll” check is less than the DC, and we expect the probability of a successful check to be low. It’s apparent from the table that this general pattern is followed, but we would like to go beyond that and justify the particular percent values and the ranges.
The values in the right-hand column of the Ability Check Success Rate table are obtained from the expression for the probability of a successful challenge, Expression (2) above. Substitute for RC using Equation (1). Substitute for DC using Equation (5). The resulting probability expression is
(6) P(d20 + modifiers >= ARC – Delta). Substitute for ARC using Equation (3). In the resulting expression, the modifiers cancel, leaving
(7) P(d20 >= 10 – Delta) as the probability that an ability check will succeed.
Now we have to determine the probability corresponding to each possible value of Delta. Here’s one way:
For a (fair) n-sided die, the probability of a roll greater than or equal to k, where k=1…n, is (n + 1 – k)/n. For a d20, the probability of a roll greater than or equal to k is (21 – k)/20:
(8) P(d20 >= k) = (21 – k)/20.
Consider the left-hand side of Equation (8), P(d20>=k). That’s just like Expression (7) above, if k and (10 – Delta) are the same. So in Equation (8), substitute (10 – Delta) for k, yielding
(9) P(d20 >= (10 – Delta)) = (21 – (10 – Delta))/20 = (11 + Delta)/20.
The probability that an ability check will succeed, in terms of Delta, the difference between the “average roll” ability check and the difficulty class, is (11 + Delta)/20.
Useful values of the probability are in the table below. The probability changes by 0.05 for each increment of Delta, so for Delta = 8, probability = 0.95; for Delta = 7, probability = 0.9, and so on. For the Ability Check Success Rate table, rather than have 20 rows in the table, I made Delta “bands” centered on these useful values.


“average roll” ability check - DC
Probability of success


9
1


4
0.75


-1
0.5


-6
0.25


-11
0

[djreynolds]

My real question, why is passive always a 10?

I understand the need for it, otherwise the game becomes bogged down with players searching every 5ft for secret doors or traps.

10 just seems high, the DC in some games is 20 and that is very achievable by a well designed character.

A 1st level rogue with expertise in perception and a 14 in wisdom, can have +6 to that roll or a passive perception of 16.

At level 13 observant, expertise, and maxed wisdom (5+10+5=20 +10=30) You cannot hide much from players. Even without expertise, a cleric or druid could have a passive check of 25 at level 13

So instead of a flat 10, what about every short rest players roll a 1d12 and the result is the number you use for your passive checks.

It adds in luck and chaos to the mix, and is easy to do. You may even get a 12.

[PhoenixPhyre]

My real question, why is passive always a 10?

I understand the need for it, otherwise the game becomes bogged down with players searching every 5ft for secret doors or traps.

10 just seems high, the DC in some games is 20 and that is very achievable by a well designed character.

A 1st level rogue with expertise in perception and a 14 in wisdom, can have +6 to that roll or a passive perception of 16.

At level 13 observant, expertise, and maxed wisdom (5+10+5=20 +10=30) You cannot hide much from players. Even without expertise, a cleric or druid could have a passive check of 25 at level 13

So instead of a flat 10, what about every short rest players roll a 1d12 and the result is the number you use for your passive checks.

It adds in luck and chaos to the mix, and is easy to do. You may even get a 12.

One of the (presumed from the design) goals of this edition is that characters that spend significant resources in something should be good at that thing. Thus, an observant (feat), expertise (class limited, non switchable) high wisdom (only works for classes that don't get expertise naturally) character Darn well better be good at finding things. They've spent most of their design resources towards that. Accept it and move on. Don't try to hobble them for some kind of enforced challenge.

[djreynolds]

One of the (presumed from the design) goals of this edition is that characters that spend significant resources in something should be good at that thing. Thus, an observant (feat), expertise (class limited, non switchable) high wisdom (only works for classes that don't get expertise naturally) character Darn well better be good at finding things. They've spent most of their design resources towards that. Accept it and move on. Don't try to hobble them for some kind of enforced challenge.

I feel ya, its the just they find everything. All the traps I set up and secret doors.

From a DM perspective, it can be demoralizing.... Tombs of Horrors is a horror for me.... the players are whooping me.

I just think a 1d12 could be cool, instead of a flat 10.

Trust me I can't make any changes.... the table would lynch me.

[Tanarii]

Then don't have perception checks automatically locate 'everything'. I mean, even the trap descriptions in the DMG don't indicate that it should just automatically let the party find a trap, but rather a trigger or even just a clue to the trigger.

As far as the challenge goes, the best traps are the ones you notice but then have to make a decision on what to do about it. Sudden surprise traps are only one kind of trap, and they're generally ones that kinda suck anyway, from a player engagement perspective. (They're probably better from a verisimilitude perspective, I'll grant.) But if players are being cautious and careful, 'gotcha' traps aren't fun. Whereas traps that require decision making once they're known about are.

[mephnick]

Tomb of Horrors wasn't designed with modern day skill checks in mind. I have no idea why they bothered updating it to 5e but I wish people would stop using it as an example for why high PP is a problem.

Traps are better when you can find them easily but still have to deal with them. High PP is a boon to the whole game.

[DivisibleByZero]

Edit: Oh yeah, this system assumes that a PC will always beat DCs of checks that are lower than its passive check, so it only increases the rate of success. Surely this is also "statistically inaccurate" as well.

It isn't "statistically inaccurate" at all, because if the DC is lower than the PC's passive check, then he doesn't need to roll at all. He passively notices it.

Personally, I don't see the need for any changes in the first place, but that's me.

[BeefGood]

What you missed is he's trying to eliminate the term 'passive' from passive skill checks, to remove the misconception that passive skill checks are only used for things that are passive on the part of the PC. As opposed to what they are defined by RAW as: "a special kind of ability check that doesn’t involve any die rolls" which "can represent the average result for a task done repeatedly" or "be used when the DM wants to secretly determine whether the characters succeed at something without rolling dice".

Thanks, yes, that is the intent of the proposed rules. But maybe a little more explanation will be helpful. The recent thread entitled "Passive Scores (other than Perception)" (sorry I don't know how to link to a thread) was the motivation. My impression of that thread was that people were making reasonable arguments for differing interpretations of passive checks, and that this was possible because the current treatment in the rulebook is not clear. So I tried to write something that can be interpreted in only one way. Specifically, I tried to write something that could be interpreted only as a way to handle ability checks when rolling isn't convenient. I wanted to discourage (or at least not encourage) the interpretation that it describes an additional ability, a "passive" ability.
That was my main motivation. A secondary motivation/goal was to provide an additional way to handle many ability checks. Currently, there's just the all-or-none method, and I wanted to provide another option.

[djreynolds]

Thanks, yes, that is the intent of the proposed rules. But maybe a little more explanation will be helpful. The recent thread entitled "Passive Scores (other than Perception)" (sorry I don't know how to link to a thread) was the motivation. My impression of that thread was that people were making reasonable arguments for differing interpretations of passive checks, and that this was possible because the current treatment in the rulebook is not clear. So I tried to write something that can be interpreted in only one way. Specifically, I tried to write something that could be interpreted only as a way to handle ability checks when rolling isn't convenient. I wanted to discourage (or at least not encourage) the interpretation that it describes an additional ability, a "passive" ability.
That was my main motivation. A secondary motivation/goal was to provide an additional way to handle many ability checks. Currently, there's just the all-or-none method, and I wanted to provide another option.

Can you explain this more.... and perhaps "dumb" it down for me? I think I would like to try this out.

[lbuttitta]

My real question, why is passive always a 10?

I understand the need for it, otherwise the game becomes bogged down with players searching every 5ft for secret doors or traps.

10 just seems high, the DC in some games is 20 and that is very achievable by a well designed character.

A 1st level rogue with expertise in perception and a 14 in wisdom, can have +6 to that roll or a passive perception of 16.

At level 13 observant, expertise, and maxed wisdom (5+10+5=20 +10=30) You cannot hide much from players. Even without expertise, a cleric or druid could have a passive check of 25 at level 13

So instead of a flat 10, what about every short rest players roll a 1d12 and the result is the number you use for your passive checks.

It adds in luck and chaos to the mix, and is easy to do. You may even get a 12.

Why does it seem odd that a level 13 character optimized to have a high passive Perception (or even a level 13 character not so optimized) would be able to detect well-hidden secret doors? I mean, a DC 25 secret door, according to the DMG, is "very hard" to detect, but at level 13, it would seem fitting to me that characters be able to overcome bigger and harder challenges, and you shouldn't have to have a character specifically built for Perception to spot a secret door with a difficulty commensurate with the party's level.

[djreynolds]

So much of the game is really tied to perception checks.

The idea of passive perception is great, but a 10 is huge when added to all the other modifiers.

I end up, to keep the game interesting, having to hound the party or up DCs.

But I'm trying the idea of a rolled score instead of passive perception, 1d12 instead of a flat 10.

I like BeefGood's idea, I just need him to explain to me..... simply. I would really like to try it out

[Tanarii]

The idea of passive perception is great, but a 10 is huge when added to all the other modifiers.

I end up, to keep the game interesting, having to hound the party or up DCs.
All passive perception does is save you from having to roll Perception checks every single round as they move along. Not only that, any group doing so is far more likely that at least one of them will roll higher than 10+perception.

If as a DM you're going to allow perception checks at all, you need to think about what qualifies for a random chance of resolution in the first place, as opposed to automatic success or failure. It's just like any other check, think about what's actually being checked for. Is it 'successfully get/bypass hidden thing' or is it 'see hidden thing, now have to make interesting decisions about it' or is it 'some hint of hidden thing and need to figure it out from there'.

The worst possible thing you can do is just jack up DCs so everyonething stays hidden. If you're going to do that, you might as well just rule them that they can't possibly succeed so there's no reason for a check in the first place.

[BeefGood]

I like BeefGood's idea, I just need him to explain to me..... simply. I would really like to try it out

Rule 1. Never say “passive perception” or “passive check.”
Rule 2. All the standard stuff about ability checks is the same—d20, ability score modifier, maybe proficiency bonus, success if greater than or equal to DC.
Rule 3. To make one or two ability checks without rolling dice,
a. Pretend the player rolled and got a 10. Add modifiers. Compare to the DC.
b. Advantage is +5, disadvantage is -5.
Rule 4. To make lots of ability checks without rolling dice, either
a. Use Rule 3, or
b. Use the table below.

Ability Check Success Rate


10 + modifiers - DC
Approximate Success Rate


7 or greater
100%


2 to 6
75%


-3 to 1
50%


-8 to -4
25%


-9 or less
0%



For example, say that a character is trying to pick seventeen locks. This character has 18 Dexterity for an ability score modifier of +4. The player is 8th level, for a proficiency bonus of +3, and is a Rogue with Expertise in Thieves’ Tools, doubling the proficiency bonus. Let’s say that these locks have DC 15. To determine the appropriate row of the table, do this math: (10 + 4 + 3 + 3) – 15. The result, 5, is in the range 2-6, which is the second row of the table. The rogue will successfully pick approximately 75%--twelve or thirteen—of the locks. There’s one more step: figuring out which locks were picked and which were not. I haven’t thought of a good way to do that.

I hope this is helpful.