Confusion of Statistical Parity and Impact Parity?

[LiFaytheGoblin]

Here: https://github.com/dssg/aequitas/blob/master/docs/source/examples/compas_demo.ipynb Under "How do I assess model fairness?" > "Pairities Calcuated" it sais

Predicted Positive Ratio k Parity	Statistical Parity

According to your definitions Predicted Positive Ratio k is PPR and Predicted Positive Ratio g is PPrev. So Aequitas defines Statistical Parity as PPR Parity That is not the definition according to Verma & Rubin 2018, who say Statistical Parity was PPrev Parity. Then again, if taking Statistical Parity synonymous to Demographic Parity, your definition of it being PPR Parity makes more sense I think.

So, any thoughts on this?