Gradient-Direction Evaluation in Differential-Privacy Model Training

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Solution Overview

Problem

Existing differential-privacy training approaches fail to effectively measure and mitigate group-group disparities in privacy costs and model accuracy, leading to higher privacy costs for underrepresented data types and inaccurate model training.

Innovation Solution

A modified differential-privacy training process that adjusts per-sample gradients adaptively based on a reference bound and clipping bound, adding noise, and evaluates gradient direction changes to balance privacy costs across groups without requiring group labels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If per-sample gradients are clipped and noise is added in differential-privacy training, then individual data sample privacy is protected, but group-group disparities in privacy costs arise

Engineering Contradiction:
Improveprivacy protectionVSAvoidgroup fairness
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent applies local quality by adjusting the clipping bound adaptively for different groups based on their representation in the training data. Underrepresented groups receive higher clipping bounds while overrepresented groups receive lower clipping bounds, creating group-specific privacy protection mechanisms rather than uniform treatment. This resolves the contradiction by maintaining privacy protection for all groups while accounting for their different contributions to the training process.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the clipping bound parameter dynamically based on group representation metrics. The clipping bound is adjusted as a function of group size or representation ratio, transforming a static privacy parameter into a dynamic one that adapts to data distribution characteristics. This allows the system to maintain differential privacy guarantees while reducing disparities across groups.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If existing differential-privacy approaches are used, then model training can proceed with privacy guarantees, but accurate measurement of group privacy costs is not possible

Engineering Contradiction:
Improveprivacy guaranteesVSAvoidgroup privacy cost measurement
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces feedback mechanisms that measure and monitor privacy costs for different groups during the training process. By calculating group-specific privacy metrics and using this information to adjust clipping bounds adaptively, the system creates a closed-loop control system that continuously optimizes privacy protection while maintaining measurement precision. This resolves the contradiction by making privacy cost measurement both possible and actionable.

Inventive Principle:
Principle #23Feedback

3Ease of manufacture

If uniform clipping bounds are applied to all samples, then implementation is simple, but underrepresented groups suffer higher privacy costs

Engineering Contradiction:
Improveimplementation simplicityVSAvoidprivacy cost distribution
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent transforms the static, uniform clipping bound into a dynamic parameter that adapts based on group representation characteristics. The clipping bound becomes a function of group size, representation ratio, or other distributional metrics, allowing the system to automatically adjust privacy protection levels. This resolves the contradiction by maintaining implementation feasibility through algorithmic adaptation rather than complex manual configuration.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS20250272436A1Identifying and mitigating disparate group impact in differential-privacy machine-learned models
Publication Date: 2025.08.28 THE TORONTO DOMINION BANK
  • US20250272436A1 patent drawing
  • US20250272436A1 patent drawing
  • US20250272436A1 patent drawing

AI summary

A model evaluation system evaluates the extent to which privacy-aware training processes affect the direction of training gradients for groups. A modified differential-privacy (“DP”) training process provides per-sample gradient adjustments with parameters that may be adaptively modified for different data batches. Per-sample gradients are modified with respect to a reference bound and a clipping bound. A scaling factor may be determined for each per-sample gradient based on the higher of the reference bound or a magnitude of the per-sample gradient. Per-sample gradients may then be adjusted based on a ratio of the clipping bound to the scaling factor. A relative privacy cost between groups may be determined as excess training risk based on a difference in group gradient direction relative to an unadjusted batch gradient and the adjusted batch gradient according to the privacy-aware training.