Layered Gradient Boosting Machine for Interpretable Insurance Pricing

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Solution Overview

Problem

Machine learning models, such as gradient boosting machines, provide predictive power but lack transparency, making it difficult to interpret the effects within decision trees, especially in insurance premium rating structures where regulators require transparent algorithms for fair treatment of customers.

Innovation Solution

A layered gradient boosting machine (LGBM) model is developed that converts records to categorical variables, selects appropriate parameters and hyperparameters, and trains decision trees with different depths to compute derivatives and update model parameters, ensuring transparency and interpretability while maintaining predictive power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If gradient boosting machines are used to improve predictive power, then predictive accuracy is improved, but transparency and interpretability deteriorate

Engineering Contradiction:
Improvepredictive accuracyVSAvoidtransparency
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent segments the gradient boosting model into multiple decision trees with different depths and structures. Each tree captures different aspects of the data, allowing the model to maintain high predictive accuracy while individual trees remain interpretable. The segmentation of complex computations into discrete, visualizable tree structures enables stakeholders to understand the decision-making process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension of interpretability by visualizing decision trees in a hierarchical structure with different depths. This dimensional transformation allows the complex multi-layered computations to be represented in a way that is both computationally effective and human-readable, resolving the contradiction between accuracy and transparency.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If complex machine learning models are used to improve predictive power, then model efficacy is improved, but algorithm transparency deteriorates

Engineering Contradiction:
Improvemodel efficacyVSAvoidalgorithm complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent divides the complex machine learning model into multiple simpler decision trees, each contributing to the overall predictive power. This segmentation maintains model efficacy while reducing the apparent complexity by breaking down the algorithm into discrete, understandable components that can be individually analyzed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent merges multiple decision trees with different depths and structures into a unified model framework. This combination allows the system to leverage the strengths of each individual tree while presenting a cohesive, interpretable structure that maintains high efficacy without excessive complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If transparent algorithms are implemented to meet regulatory requirements, then customer fairness is improved, but predictive accuracy deteriorates

Engineering Contradiction:
Improveregulatory complianceVSAvoidpredictive accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent segments the algorithm into visualizable decision trees that satisfy regulatory transparency requirements while maintaining predictive accuracy through the collective power of multiple trees. Each segmented tree can be individually reviewed for fairness, while the ensemble maintains high accuracy.

Inventive Principle:
Principle #1Segmentation

4Measurement precision

If decision trees with multiple computations are used to improve predictive power, then model accuracy is improved, but interpretability of effects deteriorates

Engineering Contradiction:
Improvemodel accuracyVSAvoideffect interpretability
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments the complex computations into distinct decision trees with different depths, making it easier to detect and measure the effect of each computational path. Each tree represents a specific decision-making pathway that can be independently analyzed for interpretability while contributing to overall accuracy.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS20230419128A1Methods for development of a machine learning system through layered gradient boosting
Publication Date: 2023.12.28 TOWERS WATSON SOFTWARE LTD
  • US20230419128A1 patent drawing
  • US20230419128A1 patent drawing
  • US20230419128A1 patent drawing

AI summary

A layered machine learning system for processing data. The machine learning system comprises decision trees with different depths. An iterative training process is performed on the layered machine learning system to determine the structures of the decision trees based on prior predictions. The fitted decision trees are further configured to update leaf values with a gradient boosting method. By cumulating the predictions of decisions trees in prior iterations, interaction effects are modeled among different depths within the layered machine learning system.