Ranking-Based Regularization for Binary Classification Models

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Solution Overview

Problem

In real-world systems with rare classes or events, conventional classification models often operate at high true positive rates, tolerating high false positive rates, which undermines user confidence and incurs additional costs, as they treat false positives and false negatives equally, failing to account for the asymmetric cost of missing critical rare cases.

Innovation Solution

A method for training a binary classifier using a ranking-based regularization approach that adjusts weights based on classification scores and ranking of positive class members, incorporating a regularization loss component to prioritize reducing false positives at high true positive rates, complementing conventional imbalanced learning losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional classification models operate at high true positive rates, then critical rare cases are detected, but false positive rates increase which undermines user confidence and incurs additional costs

Engineering Contradiction:
Improvetrue positive rateVSAvoidfalse positive rate
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies asymmetry by introducing a ranking-based regularization component that asymmetrically penalizes false positives versus false negatives. The loss function assigns different weights to ranking errors depending on the true class labels, specifically prioritizing the reduction of false positives while maintaining high true positive rates through asymmetric weighting in the regularization term

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent changes the parameter optimization approach by modifying the loss function to include a ranking-based regularization component. This component adjusts model parameters based on the relative ordering of classification scores rather than absolute score accuracy, enabling the model to learn score differentiation that reduces false positives while preserving true positive detection

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If conventional classification models treat false positives and false negatives equally, then training is simplified, but asymmetric cost of errors is not accounted for

Engineering Contradiction:
Improvetraining simplicityVSAvoiderror cost accounting
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces asymmetry in the training objective by designing a ranking-based regularization component that differentiates between false positives and false negatives. The loss function incorporates asymmetric weighting where ranking errors are penalized differently based on the true class labels, allowing the model to account for asymmetric error costs while maintaining a unified training framework

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent uses ranking-based regularization as an intermediary mechanism that bridges the gap between simple training and asymmetric error handling. This intermediary component processes classification scores through a ranking lens, transforming the training objective to implicitly account for asymmetric error costs without requiring complex separate training procedures

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS20240161008A1Ranking-based training of classification model for use with critical rare cases
Publication Date: 2024.05.16 ROYAL BANK OF CANADA
  • US20240161008A1 patent drawing
  • US20240161008A1 patent drawing
  • US20240161008A1 patent drawing

AI summary

Binary classification models can be trained to classify data as being in one of two classes. Membership in a class may be imbalanced so that there are more members in one class than the other. Additionally, one of the classes may have a higher importance than the other, yet appear much less frequently. It is possible to train the binary classification model using a base loss function and a regularization function based on a ranking of training results in order to reduce the false positives at a high true positive rate.