With tabletop roleplaying game (RPG) systems, sometimes I hear a claim that bell curve dice rolls, e.g. 3d6, are “less swingy” (less variance) than a linear based dice roll such as d20 or d%.
This is, however, incorrect.
While the distribution of dice rolls are different, the distribution of outcomes – success or failure – are the same, and for equivalent circumstances have the same statistical variance / standard deviation.
Although the outcomes have equivalent distributions, the underlying type of dice system is important for analysis of modifiers and skill progression.Continue reading 3d6 is not less swingy than d20