Charting Advantage and Disadvantage in D&D 5th Edition

There are a lot of things that I really like about 5th edition, and one of those things is advantage and disadvantage. In D&D, the primary conflict resolution mechanic is the rolling of a twenty-sided die. Roll the d20, and see if you hit some target number. Modifiers to that roll (and to the target number) reflect how good you are at that task and how difficult that task is. In previous editions, that was more or less all there was - you got a modifier for being behind soft cover, lost some modifiers for being caught unaware, and so on and so forth. 5th edition changes this, by introducing advantage and disadvantage.

• If you have advantage, roll two d20s and take the higher of the two.
• If you have disadvantage, roll two d20s and take the lower of the two.

Many of the modifiers have been thrown out in favor of this mechanic, in part so that there's less math involved. But what does this do to the numbers?

The Numbers

First off, it's important to note that advantage is not strictly better than a numerical bonus. If your target number is really high or really low, you're probably better off with the +2 (the default modifier for anything). In almost all other circumstances though, advantage is the bigger bonus. On the other hand, disadvantage also has a much bigger impact, and if you're not doing something that's trivial or impossible, it's the equivalent of a -4 to -5 negative modifier.

I've always lamented the fact that D&D lacks probability curves, which are one of the few things that dice are really good at generating. This helps to make the odds of success and failure more realistic.