Stat weighting is fairly simple to determine, once you realize the formula for how damage is calculated. Letâ€™s look, for example, at the simplest example (for a Death Knight): an instant cast spell, such as Icy Touch or Death Coil (variable assignments are given at the end of the post).
From here, it is easy to calculate what the change in damage will be if we add any amount of a given stat. For example, a change in Attack Power produces the following change in Damage.
We can just as easily use this formula to determine the change in damage if we increase the critical strike chance:
Setting these two equations equal to each other, we get:
Which can then be solved for delta_AP in terms of delta_c:
Finally, exchanging Crit Rating for Crit Chance yields the following conversion:
This is the relationship between attack power and crit rating. This formula makes sense at first glance: as the non-critical damage of an attack increases, the value of crit rating increases. Likewise, as crit chance increases, the value of additional crit rating is decresed. This relationship holds for all Death Knight instant attack spells, though it changes a bit for anything that uses weapon damage to the following:
The only thing left to do is carry out calculations for white damage, which are nearly identical, except they include haste and must be done with respect to DPS, not overall damage done.
Applying the same ideas as above, we get the following weightings:
All that is left now is to determine the weighting of Strength and Agility and combine the weightings for each attack into an overall weight scale.
Strength is really simple, you simply take the multipliers from talents and abilities to derive the final Str -> AP conversion (where FC uptime is the percent uptime of the buff):
(For most people, this will come out to about 2.6 or so)
Agility is a little tougher, since it only benefits melee attacks, so we must first convert it to crit rating and then multiply it by the percent of total damage dealt as melee:
COMBINING STAT WEIGHTS
Since the above formulas only work for individual attacks, they are not very useful for overall analysis. We must therefore combine all the various weights through a weighted average:
Stat weights for spells:
b = Base Damage AP = Current Attack Power k = Attack Power Coefficient c = Current Critical Chance (in percent) m = Critical Damage Bonus (1, w/o CSD and talents) d = Damage Done DPS = Base Weapon DPS [latex]\lambda [/latex] = Normalization Constant (3.3 for 2H, 2.4 for 1H) z = Hit Percent/Expertise w = Stat weight for an individual attack p = Percent of total damage for an individual attack W = Overall Stat weight
1) Add values for Armor Penetration (it is horribly non-linear)
2) Clean up the page format
3) Create a spreadsheet for auto-calculation of weights
1) Uploaded Beta version of the spreadsheet.