Math

To compute the expected return from a stat change, we need to know two things:

1. [Assumptions] for how the pieces fit together.
2. A [Model] for how a change in a stat (say, critical rating) will affect things it feeds into (say, critical chance).
3. The change in relevant character properties from a change in stat. In order to prevent accumulation of errors in the model, this is found by computing the property (such as expected damage dealt) at the current stat values and at the proposed new stat values, and looking at the difference between the two calculations.