Before revision:  Specifically, we study how these debiasers generalize with respect to both out-of-sample test error for computing fairness -- performance and fairness -- fairness trade-offs, and on the change in other fairness metrics that were not explicitly optimised. Our results demonstrate that out-of-sample performance on fairness and performance can vary substantially and unexpectedly. Moreover, the variance in estimation arises from class imbalances with respect to both the outcome and the protected classes. Our results highlight the importance of evaluating out-of-sample performance in practical usage .
After revision:  Specifically, we study how these debiasers generalize with respect to both out-of-sample data .