Average Damage Calculation

[sumail]

Ok so I was wondering if there is some sort of comprehensive equation for describing your average damage in terms of hit, crit, and spell power? Right now I just sort of estimate ratios between crit/hit/spell power but I figure there's a way to show how all these relate mathematical in some sort of average damage calculation.

I came up with this equation rather quickly and am not sure how correct it is.

Avg Damage = (0.83 + z)(A+Bx)(1+y*[c-1])

Where,
z = hit %
x = spell power
y = crit %

A = Base average spell dmg (basically the average dmg the spell would hit for with 0 spell power from the spells tooltip)
B = spell dmg coefficient
c = crit multiplier (2 for frost with 5/5 Ice Shards and 2.1 for fire with 5/5 ignite)

Again not sure if there are things I may have overlooked / errors in the above or if there is an equation that does this that I don't know about that someone can refer me to.

[Youfie]

I think your equation is fairly good to quickly make a decision or have a look at your DPS yeah.

You didn't take into account damage modifiers like Curses or Talents. It shouldn't be an issue in itself if you use your formula just to compare two pieces of gear etc., since they would apply to both cases in the same way.

Some other things you might want to take into account in your formula would be innate resistances, since they affect non-binary spells and are ignored by binary ones it might change things up for say, a Mage looking at a Frostbolt and a Warlock at a SB.

And maybe target resistance too, since +Hit comes down to Spell Penetration when it comes to binary spells, it might change things if the target have some removable resistance etc.

Apart from that and some other things like rolling Ignites, ISB uptime or whatever, that would be way more complex to model, your equation seems like a good start to me!

[sumail]

Yeah I suppose calling this an average damage calculation is sort of misleading. My real intent is to just have a model that allows you to look at the trade offs between different items. Normally I just used some rule of thumb raito between hit/crit/spell power which is not necessarily bad but based on the equation you see in more detail how a variation in hit/crit/spell power will affect your damage.

Also for mob resistance I'm not too familiar with how much it plays a role in raiding. I know that for mages and warlocks they have the luxury of having curses to reduce the mobs resistance which in most cases I think is enough to not need to worry about spell pen. But again i'm not too sure about it and perhaps spell pen is something else to look for with gear optimization.

[Santana]

Just get the addon Theorycraft and thank me later.

[sumail]

Yeah theorycraft is a nice addon but I prefer to do the calculations myself. I also get slightly different values than what I see in theorycraft when I use this equation.