Board Thread:League of Legends discussion/@comment-24603390-20140317093853/@comment-6016076-20160122165100

LW is a DPS multiplier. Your DPS is a product of Attack Damage, Attack Speed, Crit variables, and enemy resistance. With LW, you could say DPS resembles:

DPS = AD * AS * Crit Chance * Crit Damage * Enemy Resistance * (armor red/pen)

LW is just as related to AD as any of the others when it comes to overall DPS. If you want to talk about gold efficiency, then you have to include all the variables.

For example, you can have 1000 AD and your  graph would show armor pen to always be the most efficient option even when the opponent has low armor, when in reality, especially against low armor opponents, the  most gold efficient option would be to buy some attack speed or crit.