Federated learning allows us to run machine learning algorithms on
decentralized data when data sharing is not permitted due to privacy concerns.
Ensemble-based learning works by training multiple (weak) classifiers whose
output is aggregated. Federated ensembles are ensembles applied to a federated
setting, where each classifier in the ensemble is trained on one data location.
In this article, we explore the use of federated ensembles of Bayesian
networks (FBNE) in a range of experiments and compare their performance with
locally trained models and models trained with VertiBayes, a federated learning
algorithm to train Bayesian networks from decentralized data. Our results show
that FBNE outperforms local models and provides a significant increase in
training speed compared with VertiBayes while maintaining a similar performance
in most settings, among other advantages. We show that FBNE is a potentially
useful tool within the federated learning toolbox, especially when local
populations are heavily biased, or there is a strong imbalance in population
size across parties. We discuss the advantages and disadvantages of this
approach in terms of time complexity, model accuracy, privacy protection, and
model interpretability.