Social Foundations of Computation Conference Paper 2024

Unprocessing Seven Years of Algorithmic Fairness

Seven years ago, researchers proposed a postprocessing method to equalize the error rates of a model across different demographic groups. The work launched hundreds of papers purporting to improve over the postprocessing baseline. We empirically evaluate these claims through thousands of model evaluations on several tabular datasets. We find that the fairness-accuracy Pareto frontier achieved by postprocessing contains all other methods we were feasibly able to evaluate. In doing so, we address two common methodological errors that have confounded previous observations. One relates to the comparison of methods with different unconstrained base models. The other concerns methods achieving different levels of constraint relaxation. At the heart of our study is a simple idea we call unprocessing that roughly corresponds to the inverse of postprocessing. Unprocessing allows for a direct comparison of methods using different underlying models and levels of relaxation. Interpreting our findings, we recall a widely overlooked theoretical argument, present seven years ago, that accurately predicted what we observe.

Author(s): Cruz, André F. and Hardt, Moritz
Book Title: The Twelfth International Conference on Learning Representations (ICLR 2024)
Year: 2024
Month: May
Project(s):
Bibtex Type: Conference Paper (inproceedings)
State: Published
URL: https://openreview.net/pdf?id=jr03SfWsBS
Electronic Archiving: grant_archive
Links:

BibTex

@inproceedings{cruz2024unprocessing,
  title = {Unprocessing Seven Years of Algorithmic Fairness},
  booktitle = {The Twelfth International Conference on Learning Representations (ICLR 2024)},
  abstract = {Seven years ago, researchers proposed a postprocessing method to equalize the error rates of a model across different demographic groups. The work launched hundreds of papers purporting to improve over the postprocessing baseline. We empirically evaluate these claims through thousands of model evaluations on several tabular datasets. We find that the fairness-accuracy Pareto frontier achieved by postprocessing contains all other methods we were feasibly able to evaluate. In doing so, we address two common methodological errors that have confounded previous observations. One relates to the comparison of methods with different unconstrained base models. The other concerns methods achieving different levels of constraint relaxation. At the heart of our study is a simple idea we call unprocessing that roughly corresponds to the inverse of postprocessing. Unprocessing allows for a direct comparison of methods using different underlying models and levels of relaxation. Interpreting our findings, we recall a widely overlooked theoretical argument, present seven years ago, that accurately predicted what we observe.},
  month = may,
  year = {2024},
  slug = {cruz2024unprocessing},
  author = {Cruz, André F. and Hardt, Moritz},
  url = {https://openreview.net/pdf?id=jr03SfWsBS},
  month_numeric = {5}
}