Achieving Fairness in Human-Centered Federated Learning without Demographic Information

Core Concepts

A novel approach, Hessian-Aware Federated Learning (HA-FL), achieves fairness in human-centered federated learning systems without requiring knowledge of sensitive attributes or bias-inducing factors.

Abstract

The paper presents a novel approach called Hessian-Aware Federated Learning (HA-FL) that addresses the challenge of ensuring fairness in human-centered federated learning (FL) systems without requiring knowledge of sensitive attributes or bias-inducing factors.
Key highlights:

Existing fairness strategies in FL require access to sensitive attribute information, which contradicts FL's privacy-preserving principles. Moreover, human-centered datasets often lack explicit information about sensitive attributes.
HA-FL introduces a fairness-promoting approach inspired by "Fairness without Demographics" in machine learning. It minimizes the top eigenvalue of the Hessian matrix during local training to ensure equitable loss landscapes across FL participants, achieving fairness without needing sensitive attribute knowledge.
HA-FL also includes a novel FL aggregation scheme that promotes participating models based on error rates and loss landscape curvature attributes, further fostering fairness across the FL system.
Comprehensive evaluations on three real-world human-centered datasets demonstrate HA-FL's effectiveness in balancing fairness and efficacy, even in scenarios involving single or multiple bias-inducing factors, without requiring sensitive attribute information.
HA-FL represents a significant advancement in enabling fair and privacy-preserving human-centered FL, paving the way for more equitable decentralized AI applications.

Stats

The paper does not provide specific numerical data or metrics in the main text. However, it presents comprehensive evaluation results in tables, comparing the performance of HA-FL with other federated learning approaches across various datasets and fairness metrics.

Quotes

"Federated learning (FL) enables collaborative model training while preserving data privacy, making it suitable for decentralized human-centered AI applications."
"However, a significant research gap remains in ensuring fairness in these systems. Current fairness strategies in FL require knowledge of bias-creating/sensitive attributes, clashing with FL's privacy principles."
"To tackle these challenges, we present a novel bias mitigation approach inspired by 'Fairness without Demographics' in machine learning."

Key Insights Distilled From

Fairness Without Demographics in Human-Centered Federated Learning

by Roy Shaily,S... at arxiv.org 05-01-2024

https://arxiv.org/pdf/2404.19725.pdf

Deeper Inquiries

How can the HA-FL approach be extended to handle dynamic changes in the client population or data distributions during the federated learning process?

The HA-FL approach can be extended to handle dynamic changes in the client population or data distributions by incorporating adaptive mechanisms that adjust to these changes in real-time. Here are some strategies to achieve this:

Dynamic Weighting: Implement a dynamic weighting mechanism that adjusts the importance of each client's contribution based on their performance metrics. Clients with more accurate and fair models could be given higher weights, while those with lower performance could be downweighted.

Adaptive Learning Rates: Utilize adaptive learning rate algorithms that can adjust the learning rates for individual clients based on their convergence speed and model performance. This can help in accommodating changes in data distributions and client populations.

Model Reinitialization: Periodically reinitialize the global model based on the current state of the clients to prevent bias accumulation and ensure that the model adapts to the changing data distributions.

Client Selection: Implement a dynamic client selection strategy that prioritizes clients with more representative data or those that contribute to reducing bias in the overall model. This can help in maintaining fairness and accuracy in the face of changing client populations.

Continuous Monitoring: Set up a monitoring system that continuously evaluates the performance and fairness metrics of individual clients and triggers retraining or model updates when significant changes are detected.

By incorporating these adaptive mechanisms, the HA-FL approach can effectively handle dynamic changes in the client population or data distributions, ensuring fairness and accuracy in federated learning systems.

What are the potential limitations or drawbacks of the Hessian-based fairness optimization approach, and how can they be addressed?

While the Hessian-based fairness optimization approach used in HA-FL offers several advantages, it also comes with potential limitations and drawbacks that need to be addressed:

Computational Complexity: Calculating the Hessian matrix and its eigenvalues can be computationally expensive, especially for large-scale models and datasets. This can lead to increased training times and resource requirements.

Sensitivity to Noise: The Hessian matrix calculations can be sensitive to noise in the data, which may affect the accuracy of the eigenvalues and, consequently, the fairness optimization process.

Hyperparameter Sensitivity: The approach may be sensitive to hyperparameters, such as the weighting factor α, which balances accuracy and fairness objectives. Improper tuning of these hyperparameters can impact the effectiveness of the fairness optimization.

Limited Generalization: The Hessian-based approach may have limitations in generalizing to diverse datasets and scenarios, especially when the underlying data distributions are complex or non-linear.

To address these limitations, the following strategies can be considered:

Efficient Approximations: Implement more efficient approximations or sampling techniques to estimate the Hessian matrix and eigenvalues, reducing computational overhead.

Noise Robustness: Introduce noise-robust techniques or regularization methods to make the fairness optimization process more resilient to noisy data.

Automated Hyperparameter Tuning: Utilize automated hyperparameter tuning algorithms to find optimal values for hyperparameters like α, ensuring robustness and adaptability across different settings.

Model Regularization: Incorporate regularization techniques to improve the generalization capabilities of the fairness optimization approach and enhance its performance on diverse datasets.
By addressing these limitations and implementing the suggested strategies, the Hessian-based fairness optimization approach can be enhanced for more robust and effective fairness optimization in federated learning systems.

What other techniques or insights from the "Fairness without Demographics" literature could be leveraged to further enhance fairness in human-centered federated learning systems?

Several techniques and insights from the "Fairness without Demographics" literature can be leveraged to further enhance fairness in human-centered federated learning systems:

Instance Reweighting: Adopt instance reweighting techniques that focus on boosting instances that are underrepresented or have been subject to bias, without explicitly considering demographic attributes. This can help in achieving fairness without relying on sensitive information.

Knowledge Distillation: Explore knowledge distillation methods that transfer fairness-related knowledge from pre-trained models to federated learning models, without sharing sensitive attributes. This can help in improving fairness without compromising privacy.

Adversarial Learning: Implement adversarial learning approaches that introduce adversarial perturbations to the training process, aiming to reduce bias and enhance fairness without the need for demographic information.

Fairness Regularization: Introduce fairness regularization terms in the loss function that penalize unfair predictions or decisions, promoting fairness in the model's outputs across different groups or distributions.

Fairness-aware Aggregation: Develop aggregation strategies that prioritize models based on fairness metrics, such as equal opportunity or disparate impact, to ensure fairness in the final federated model without requiring demographic attributes.

By incorporating these techniques and insights from the "Fairness without Demographics" literature, human-centered federated learning systems can achieve enhanced fairness while upholding privacy and data protection principles.