Continuous Fair SMOTE -- Fairness-Aware Stream Learning from Imbalanced Data
This addresses fairness and class imbalance issues in evolving data streams for applications like online decision-making, though it is incremental as it builds on existing SMOTE methods.
The authors tackled the problem of ensuring fairness and handling class imbalance in online machine learning data streams by proposing CFSMOTE, a fairness-aware variant of SMOTE. The result showed significant improvements in group fairness metrics compared to vanilla C-SMOTE while maintaining competitive performance.
As machine learning is increasingly applied in an online fashion to deal with evolving data streams, the fairness of these algorithms is a matter of growing ethical and legal concern. In many use cases, class imbalance in the data also needs to be dealt with to ensure predictive performance. Current fairness-aware stream learners typically attempt to solve these issues through in- or post-processing by focusing on optimizing one specific discrimination metric, addressing class imbalance in a separate processing step. While C-SMOTE is a highly effective model-agnostic pre-processing approach to mitigate class imbalance, as a side effect of this method, algorithmic bias is often introduced. Therefore, we propose CFSMOTE - a fairness-aware, continuous SMOTE variant - as a pre-processing approach to simultaneously address the class imbalance and fairness concerns by employing situation testing and balancing fairness-relevant groups during oversampling. Unlike other fairness-aware stream learners, CFSMOTE is not optimizing for only one specific fairness metric, therefore avoiding potentially problematic trade-offs. Our experiments show significant improvement on several common group fairness metrics in comparison to vanilla C-SMOTE while maintaining competitive performance, also in comparison to other fairness-aware algorithms.