How do you mathematically decide what's better?

[Deleted]

Let's say you have these two items:

ww.wowhead.com/item=86750
ww.wowhead.com/item=86899
(add w)

Now I know most of the time you can tell just by looking at the stats which is better for your class/spec. But let's say I want to calculate how good they are using the stat weights over at EJ, how do you do it? What's the formula?

[Deleted]

Well for the best results you need to calculate your own EP values in simcraft. But to answer your question, say haste is worth 1 EP and crit is worth 2 EP you just add up the values and see which one gives the most EP. These are made up numbers by the way so don't use those.

Once you know how much a certain stat is worth all that you have left to do is add them all up based on how much they are worth.

[Kael]

For the best napkin approximation, substitute your best secondary stat for hit and expertise (as having them generally allows you to reforge into your top stat somewhere else; single exception being non-exp-capped assassination), do a 40% reforge to your best stat from the item's worst stat, sub a gem, and multiply by EP values. Preferably yours.

Significantly better method: open your character up on http://shadowcraft.mmo-mumble.com/ or through SimulationCraft, and on the former, optimize gems/reforging, check effect for both items, or for the latter, reforge/re-gem properly in the code or using one of the import sites, and sim yourself with either belt on.

ShadowCraft will save you the most time for highly accurate results, and provides EP weights for your current gear, allowing you to follow Bovan's last step without checking your EP through SimC.

[shadowboy]

The formula is stat1_amount*stat1_weight + stat2_amount*stat2_weight until you sum over all stats.

Example, say agi has an EP of 2.7, haste has an EP of 1.5, and crit has an EP of 1.2, say a piece has 1000 agility, 682 haste, and 652 crit.

The EP value of the piece would be 1000*2.7 + 682*1.5 + 652*1.2 = 4505.4 EP

[Deleted]

I guess OP wants to know more about the maths itself, rather than how to do it - at least he sounds like so, to me. Check the sources of the most used and trusted rogue dps tools: https://github.com/Aldriana/ShadowCraft-Engine ; https://github.com/Pathal ; http://code.google.com/p/simulationc...ource/checkout