Private database join performed by Retency delivers Differentially Private datasets which train AI models as accurately as non-private data. This page contains an example of analyses that illustrate how Retency Privacy Engine protects training of your usual AI tool.

For this, it is interesting to compare how Machine Learning models are trained in one of the two situations:

• Model is trained with Differentially Private datasets generated by Retency Privacy Engine, or:
• Model is trained with non-anonymized raw data.

Approach

The objective is to train a predictive model providing the probability of lung cancer based on certain individual living habits. For this, it is necessary to create a training dataset that results from the line-by-line association of two databases sharing the same individual identifier:

• Database extract A contains individual descriptive attributes for a population of 100 000 individuals: age group, sex, urban density of residence, and smoking habit;
• Table B is extracted from health records for the same population and contains the target variable: whether individuals have contracted a lung cancer.

A priori, model training would require a non-confidential a line-by-line join between the two tables.

Two AI models using the same algorithm are set up:

• One model is trained with the basic join on identifiers of the two tables;
• One model is trained with a table reconstructed from the Differentially Private aggregates generated by Retency.

The training results for both models are compared:

• On one hand, the non-anonymized dataset is used for both training and validation;
• On the other hand, training is made with the differentially confidential dataset for training and the original dataset for validation.

The same process is performed with 3 types of machine learning algorithms: Logistic Regression, XGBoost and Random Forests.

Characteristics of test data used

The test data contains infrequent situations that aptly test the capacity of Retency Privacy Engine to detect weak signals. The total dataset counts 100K individuals. The partition of the dataset in subsets where all individuals share the same attributes and target variable counts 121 subsets. Subset distribution by cardinality is summarized below. For instance, 25.4% of subsets contain less than 0.1% of the total population, with an average cardinal equal to 0.048% of the total population.

Results using Logistic Regression

In this section, logistic regression algorithms are used. The model implementation uses scikit-learn packages in python scripts.

The table below shows the excellent correspondence between the two models in terms of performance and feature importance.

Results using XGBoost

In this section, datasets educate XGBoost models. The model implementation uses scikit-learn packages in python scripts.

The table below shows the nearly-perfect correspondence between the two models in terms of performance and feature importance.

Results using Random Forests

In this section, datasets educate Rand Forests models. The model implementation uses scikit-learn packages in python scripts.

The table below shows the perfect correspondence between the two models in terms of performance and feature importance.