D&D 4E Heavy Concrete Data on 4e's Skill Challenge System (long, lots of tables)

[Tervin]

I have a question:

The PWR for a 1st level party on the first page is listed as 7.3%, or 0.073.

It seems that if I follow your working from the other thread:

p(5 wins) = 0.5 ^ 5 = 0.03125
p(4 wins, 1 loss in any order) = 0.5^5 * 5c4 = 0.03125 * 5 = 0.15625

Totalled up I get 0.1875, or 18.75%.

Did I mess something up there? It seems most likely that you've assumed that one or more characters are using their bad skill levels, which isn't what's stated in the assumptions.

You have the correct calculations for a Complexity 1 challenge. He ran a Complexity 5 challenge.

 

[On Puget Sound]

Here is an Aid Another house rule I just came up with:
Aid Another does not have DC 10, it has DC (action you are trying to aid)-5. So aiding a DC 20 action is DC 15. And failure by 0-4 has no effect, but failing by 5 or more gives a -2 penalty as you get in the way, give bad advice, etc.

Comments?

 

[Spatula]

But, the point is, the system is rewarding groups who work together as a team to improve their odds from 50/50, to much higher percentages. If you get your odds to 90/10, for instance, then your chances of overall success are pretty high.

I'm still thinking that this is actually a feature, not a bug.

Well, they're actually improving their odds from 10-20%, not 50%.

How you see it all depends on what you want out of skill challenges. The DMG doesn't present a solid explination of what they're supposed to achieve. To me, based on what was said about the system over the past several months, skill challenges are a way to engage the whole party in a skill-based encounter, rather than everyone sitting around while one guy makes his checks. To that end, everyone aiding another for that one guy doesn't change anything. In a way it's worse because it's just busy work for the other players. "Here, make a trivial DC 10 check while someone else does the fun stuff." That sort of limelight-hogging, I feel, runs very counter to the overall 4e design goals, so I do not think that it's what was intended. I also find it a little bizarre for anyone behind the goals of 4e's design to be sticking up for "everyone get a snack while Joe makes his rolls" gameplay.

Naturally if you don't have a problem with using skill challenges like that, then it's a feature. As long as everyone can aid another, anyway, since if a few of them can't they're very likely to fail. "Uh oh, Bob isn't here this week... can we just roll his aid checks for him?"

EDIT: just to give a better idea of where I'm coming from, when I think back on the reports from DDXP and other demo games about the Escape from Sembia skill challenge, never once did I hear anyone mention aid another actions being used. Each character was doing something particular to their character in order to advance the group's goal of evading the guards. That formed my impression of what skill challenges are supposed to be.

 

[gribble]

Here is an Aid Another house rule I just came up with:
Aid Another does not have DC 10, it has DC (action you are trying to aid)-5. So aiding a DC 20 action is DC 15. And failure by 0-4 has no effect, but failing by 5 or more gives a -2 penalty as you get in the way, give bad advice, etc.

Comments?

I'd tend to just you the appropriate "easy" DC for the PCs level. I think that reflects the intent (an easier skill check to assist someone maker a harder one).

I'm still not sure about everyone cooperating on every skill check "for free". It's certainly a different way to approach things from the 3.x rules. It would make the uses of skills that add a +2 to another check a lot more useful (both because they're more likely to succeed, and because they'd give another +2 bonus on top of the usual cooperation)...

 

[Tervin]

I'd tend to just you the appropriate "easy" DC for the PCs level. I think that reflects the intent (an easier skill check to assist someone maker a harder one).

I'm still not sure about everyone cooperating on every skill check "for free". It's certainly a different way to approach things from the 3.x rules. It would make the uses of skills that add a +2 to another check a lot more useful (both because they're more likely to succeed, and because they'd give another +2 bonus on top of the usual cooperation)...

Easy DC sounds like a good idea - basically meaning 5 less than it should have been otherwise (if you like me don't intend to ever look at any tables to find the right DC in a skill challenge).

I will allow Aid Another when it makes obvious sense, and when the player who wants to use it can make it seem like it makes sense with how he plays it.

 

[Spatula]

I'd tend to just you the appropriate "easy" DC for the PCs level. I think that reflects the intent (an easier skill check to assist someone maker a harder one).

See the urban chase template, and some of the others. That's basically how those challenges handle "aiding" without actually using aid another (and it implies that aiding is not a matter of course for skill challenges).

 

[thomasberg1974]

I'm impressed by the complexity of your analysis, but I'd like to try a simpler and more intuitive approach when judging skill challenges.

First of all, lets assume that the PCs are supposed to be winning the skill challenges, just like they're supposed to be winning most of the combat encounters. Some of them should be very hard, and perhaps be close calls, but our heroes are supposed to come out victorious in the end. A failure or two shouldn't hurt once in a while - and failing skill challenges are not nearly as terrible as losing a combat encounter...

My next assumption is that the primary skill user for each check is trained and has a decent score. For a 1st level character that'd be about a total skill score of 9.

Furthermore, my players like to help each other out - like they do during most combat encounters. However, not all of them can help on all skill checks. In my experience, there'd be about 2-3 actually aiding with each check. While I realize aid another will become automatic as the characters increase in level, and the DC for aid doesn't change by tier, there is usually some situation to limit how many who can practically be of help (space, combat, personality, etc.).

We'll go with 2 as a basic number of helping hands, providing a total of +4, giving the primary skill user a total score of 13 and a success chance of about 70% with each check. While it should be quite possible to roll under 30% two times on 5 checks (for a complexity 1 challenge) or 5 times over 14 rolls (for a complexity 4 challenge), success should be the most common result. In fact, a quick number crunch tells me that my score of 13 would work out in roughly 55% of the cases for a complexity 1 challenge.

A look at the other end of the scale, at high level charactes should give somewhat similar results. Our 25th level skill user has a skill score of about 12 (level) + 5 (trained) + 6 (ability and other stuff) for a total of 23. With his helping hands increased to 3 people on average, he'll have a score of 29 for moderate DCs of 33 that'll give us 15% chance of failure for each attempt. This should work in about 85% of the cases.

Conclusion: Skill chances work the way they are written, as long as the DM uses common sense in limiting aid to practical circumstances and develops challenges that use a variety of skills that can't be won by maximizing a single skill.

 

[Tervin]

I'm impressed by the complexity of your analysis, but I'd like to try a simpler and more intuitive approach when judging skill challenges.

/---/

Conclusion: Skill chances work the way they are written, as long as the DM uses common sense in limiting aid to practical circumstances and develops challenges that use a variety of skills that can't be won by maximizing a single skill.

I think I get your reasoning. And I think it works. Sometimes. You say that losing matters less than losing a combat. Obviously true. You also say that Aid Another should be allowed when it fits, to the extent that it makes sense. Totally agreed. And you say that more than one skill should be involved in a skill challenge. Absolutley agreed. In fact I can't see myself running a skill challenge where I would allow use of only one skill all the way through. That sounds just repetetive and boring.

But... you are only taking into the cases where you can do things like this and it makes sense. A skill challenge that has to do with getting past a hazard or a trap - well there this could very well work. A chase scene through a city? Perhaps, but not as much. A social encounter? I am sorry, but no.

In other words skill challenges where Aid Another is not a reasonable approach are those cases where we should have to accept the PCs are likely to fail, and that it doesn't matter because it is not as bad as losing a combat. Or at least that is what I get from your post. I think you can understand why I don't totally agree with that.

 

[Contents May Vary]

[EDIT: See later messages - I was neglecting to add 5 to the skill challenge DCs. If I do so, the figures below change to be comparable to the ones posted elsewhere]

I don't believe that the figures presented in the tables in this thread are correct.

I will present in my next posting a C# program that I wrote to check things out. In this post, I shall post the results of running that program.

I'm going to concentrate here on easy, moderate and hard difficulty skill challenges for level 7 characters.
I'm only going to present the results for a complexity 5 challenge, where you need to get 12 successes before failing 6 times.

According to page 42 of the DMG, for level 7 characters the DCs of the challenges are as follows:

Easy: 15
Moderate: 19
Hard: 23

I will present the results for a single character attempting the challenge, with no assistance and for a variety of character skill levels.

These are the results I got for a complexity 5 challenge:

Easy challenge (DC = 15)

Skill = 5, DC = 15, %success = 14.64
Skill = 6, DC = 15, %success = 26.46
Skill = 7, DC = 15, %success = 41.71
Skill = 8, DC = 15, %success = 59.60

Moderate challenge (DC = 19)

Skill = 7, DC = 19, %success = 2.98
Skill = 9, DC = 19, %success = 14.68
Skill = 11, DC = 19, %success = 41.83
Skill = 12, DC = 19, %success = 59.87
Skill = 13, DC = 19, %success = 76.44

Hard challenge (DC = 23)

Skill = 9, DC = 23, %success = 0.31
Skill = 11, DC = 23, %success = 3.05
Skill = 13, DC = 23, %success = 14.62
Skill = 15, DC = 23, %success = 41.94
Skill = 16, DC = 23, %success = 59.78

My interpretation:

For an easy difficulty complexity 5 challenge, an unaided character's skill must be at least 8 to have a greater than 50% chance of success.

For a moderate difficulty complexity 5 challenge, an unaided character's skill must be at least 12 to have a greater than 50% chance of success.

For a hard difficulty complexity 5 challenge, an unaided character's skill must be at least 16 to have a greater than 50% chance of success.

These numbers seem fairly reasonable to me. A hard challenge is going to be pretty hard...
A reasonable high skill for a character at level 7 would be 13: +5 for training in that skill, +2 for racial bonus, +3 for ability bonus, +3 for 1/2 level. Such a character would only have around a 15% chance of passing such a hard challenge. That seems ok - it's supposed to be hard!

If that character also had skill focus (for a skill of 16), they would have nearly 60% chance of passing.
If instead another character aided them (for a skill of 15), they would still have more than 40% chance of passing.

The moderate challenge would be very easy for such a character, even without the skill focus or another character's help.
They would have a more than 75% chance of passing a moderate challenge.

Seems fine to me...

 

[Contents May Vary]

The code (excuse formatting!)

public class Program
{
    public static void Main()
    {
        Random rng = new Random();

        Console.WriteLine("\nEasy challenge (DC = 15)\n");
        tryChallenge(100000,  5, 15, 12, 6, rng);
        tryChallenge(100000,  6, 15, 12, 6, rng);
        tryChallenge(100000,  7, 15, 12, 6, rng);
        tryChallenge(100000,  8, 15, 12, 6, rng);

        Console.WriteLine("\nModerate challenge (DC = 19)\n");
        tryChallenge(100000, 7, 19, 12, 6, rng);
        tryChallenge(100000, 9, 19, 12, 6, rng);
        tryChallenge(100000, 11, 19, 12, 6, rng);
        tryChallenge(100000, 12, 19, 12, 6, rng);
        tryChallenge(100000, 13, 19, 12, 6, rng);

        Console.WriteLine("\nHard challenge (DC = 23)\n");
        tryChallenge(100000, 9, 23, 12, 6, rng);
        tryChallenge(100000, 11, 23, 12, 6, rng);
        tryChallenge(100000, 13, 23, 12, 6, rng);
        tryChallenge(100000, 15, 23, 12, 6, rng);
        tryChallenge(100000, 16, 23, 12, 6, rng);
    }

    private static void tryChallenge
    (
        int    numTrials,
        int    skill,
        int    dc,
        int    requiredSuccesses,
        int    maxFailures,
        Random rng
    )
    {
        double successRatio = successRate
        (
            numTrials, 
            skill, 
            dc, 
            requiredSuccesses, 
            maxFailures, 
            rng
        );

        double percentSuccess = 100 * successRatio;

        Console.WriteLine
        (
            string.Format
            (
                "Skill = {0}, DC = {1}, %success = {2:f2}",
                skill, dc, percentSuccess
            )
        );
    }

    private static double successRate
    (
        int    numTrials,
        int    skill,
        int    dc,
        int    requiredSuccesses,
        int    maxFailures,
        Random rng
    )
    {
        int totalSuccesses = 0;

        for (int i = 0; i < numTrials; ++i)
        {
            if (attemptChallenge(skill, dc, requiredSuccesses, maxFailures, rng))
            {
                ++totalSuccesses;
            }
        }

        return ((double)totalSuccesses)/numTrials;
    }

    private static bool attemptChallenge
    (
        int    skill,
        int    dc,
        int    requiredSuccesses,
        int    maxFailures,
        Random rng
    )
    {
        int successes = 0;
        int failures = 0;

        for (;;)
        {
            // Note: rng.Next(x) returns number from 0..(x-1).
            // So we must add 1 to it to get 1..x.

            int skillRoll = skill + 1 + rng.Next(20); 

            if (skillRoll >= dc)  // Succeeded?
            {
                if (++successes >= requiredSuccesses)
                {
                    return true;
                }
            }
            else  // Failed.
            {
                if (++failures >= maxFailures)
                {
                    return false;
                }
            }
        }
    }
}