D&D 5E Rolling for All Spells

[Ultimatecalibur]

First of all we are talking two things. If you are talking about the average over the span then yes the average roll is 10.5 on a d20 but what is the average on a single instance? There is not one. It is equally able to come up any number on the die. So it is helpful to look at the instance rather than the span. Contests are usually only a few rolls and not 20 or more which it would take to get to the 10.5 number.

Wrong again. No matter if it is a single roll or a 1000 rolls, when you roll a d20 the average roll will always be 10.5. That is what you get when you have a die numbered 1 through 20 and each side has a 5% chance of being landed on.

As to the d39 I am aware it does not work like a d39 but it is a useful tool to show the randomness. 400 possibilities split into 39 potential roll totals (-19 to +19). I don't dispute your statistics my beef with contests is their randomness. Are you claiming they are more random, less random, or are the same random? I think your argument is that they are the same. Is that right?

Yes, they have the same randomness. A coin flip, getting a 1, 2, or 3 on a d6, evens on a d10, rolling a 11+ on a d20, rolling below 51 on a d100, having a positive total with d20-d20 with a 50% chance of 0 being positive, and many others all have a 50% chance of happening. A 50% probability is a 50% probability no matter the variance.

 

[Sadrik]

Wrong again. No matter if it is a single roll or a 1000 rolls, when you roll a d20 the average roll will always be 10.5. That is what you get when you have a die numbered 1 through 20 and each side has a 5% chance of being landed on.

Hahaha, your are arguing for a mathematical construct that only becomes accurate with lots of rolls. I suppose we are going to have to disagree. If you roll it once, one face including 10 or 11 will come up 5% of the time which is equal to all of the other faces. Contests are only made in small amounts and for the average roll to come through you have to roll lots of times. DM says roll opposed diplomacy, player picks up die and tosses it once and determines outcome based on what the DM rolled. They do not roll 20+ times to be able to achieve an average.

Yes, they have the same randomness. A coin flip, getting a 1, 2, or 3 on a d6, evens on a d10, rolling a 11+ on a d20, rolling below 51 on a d100, having a positive total with d20-d20 with a 50% chance of 0 being positive, and many others all have a 50% chance of happening. A 50% probability is a 50% probability no matter the variance.

You know when people say statistics are all crap and they can be manipulated to say anything. I really feel like that is what you are doing. I don't know if you are willfully trying ignore the point or are just not getting it. I dont know. So you think contested rolls have the same randomness, you also think that +1 modifier is having the same effect on a roll when you have 20 possible results on a d20 as 39 possible results on a d20-d20. This is really the crux of it right here.

Think of it this way, I will use an extreme example so that you see the disparity. If you roll a d10 and add 1 that plays more influence on the result that if you rolled 1d100 and added 1 to it. In 3e due to grappling being opposed rolls, you saw huge grapple modifiers just so large monsters would not accidentally get grappled by smaller ones. This was done to combat the swingyness of the mechanic (39 vs. 20). We have seen in the past optional opposed roll rules where attacks and saves could be done with opposed rolls. These were never popular because there was no baseline of defense.

So two concepts, contests are not many rolls to resolve the task and 39 possibilities vs. 20.

 

[Blackbrrd]

I checked out the different results when rolling d20-d20 and really, it's nothing even similair to roling a d20-10 vs defense. It becomes a bit obvious since the results can be between -19 and +20 instead of from -9 to +10. If you want opposed checks, you probably want d10's instead of d20's. As Sadrik noted (regarding grapple), you would otherwise need huge modifieres before they mean much.

... on the other hand the effect while rolling d20-d20 might be what you are after? Letting the modifiers play a smaller role? Anyway, the math of d20-d20 is too much for me at the moment. I managed to get a bit confused when just running all 400 combinations in Excel. Mostly because of the fact that the range is far bigger than with just a d20.

Anyway, a d20-d20 is much more likely to have a result around 0 than d39-20. And the d39 is much more likely to have a result around +20/-19 than the d20-d20. The average is the same, but the variance is smaller for d20-d20.

Anyway, I think they should just go with the attacker rolling a single d20. It's half as much rolling and math. In addition, looking at much harder it is to calculate the probability of hitting and such, I think it just complicates and obfuscates the game too much.

 

[Dausuul]

So two concepts, contests are not many rolls to resolve the task and 39 possibilities vs. 20.

No. There are two possibilities. You succeed, or you fail. Numbers on the dice are just the mechanism you use to get to those outcomes. If you have a 50% chance of success, it doesn't matter if the road to that 50% probability involves a hundred rolls or one, you will succeed half the time and you will fail half the time. End of story.

Think of it this way, I will use an extreme example so that you see the disparity. If you roll a d10 and add 1 that plays more influence on the result that if you rolled 1d100 and added 1 to it. In 3e due to grappling being opposed rolls, you saw huge grapple modifiers just so large monsters would not accidentally get grappled by smaller ones. This was done to combat the swingyness of the mechanic (39 vs. 20). We have seen in the past optional opposed roll rules where attacks and saves could be done with opposed rolls. These were never popular because there was no baseline of defense.

This much is true: Opposed rolls shrink the impact of any given modifier on the d20 roll, and this effect becomes more pronounced as the modifier gets bigger. That's the real difference between opposed rolls and straight roll versus a DC; opposed rolls lead to diminishing returns as your modifier increases, at least until you hit the "cap" of 95% imposed by automatic failure on a 1.

 

[Weather Report]

53% of all statistics are made up.