Attack Speed

I've often seen people say IAS of 33% => +50% damage. I've seen this often enough that I assume this is right, but could someone explain to me why? Is the counterintuitive nature of this purely maths based or related to game mechanics? Either way I'd like an explanation, or link to one. Thanks.

First of all, "increased attack speed" is a misnomer. It really should be "reduced attack duration." You have not gone from X attacks/sec to (4/3)*X attack/sec; rather you have gone from Y sec/attack to (2/3)*Y sec/attack.

With that straightened out, the math makes more sense. Start with the definition of DPS, DPS = damage/sec. 33%IAS multiples the sec in the denominator by 2/3. Which, elementary school fraction lessons teach us, is equivalent to multiplying the entire term by 3/2. To balance the equation, what you do on the right, you must do on the left. So the effect of multiplying the seconds by 2/3 is to multiply the DPS by 3/2. 3/2 is 50% more than 1. Thus, a 50% increase in DPS.

Thank you, just what I was looking for.