A Unified Theory of Diversity in Ensemble Learning

Fuente: arXiv
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Autores principales: Wood, Danny, Mu, Tingting, Webb, Andrew, Reeve, Henry, Luján, Mikel, Brown, Gavin
Formato: Preprint
Publicado: 2023
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author Wood, Danny
Mu, Tingting
Webb, Andrew
Reeve, Henry
Luján, Mikel
Brown, Gavin
author_facet Wood, Danny
Mu, Tingting
Webb, Andrew
Reeve, Henry
Luján, Mikel
Brown, Gavin
contents We present a theory of ensemble diversity, explaining the nature of diversity for a wide range of supervised learning scenarios. This challenge has been referred to as the holy grail of ensemble learning, an open research issue for over 30 years. Our framework reveals that diversity is in fact a hidden dimension in the bias-variance decomposition of the ensemble loss. We prove a family of exact bias-variance-diversity decompositions, for a wide range of losses in both regression and classification, e.g., squared, cross-entropy, and Poisson losses. For losses where an additive bias-variance decomposition is not available (e.g., 0/1 loss) we present an alternative approach: quantifying the effects of diversity, which turn out to be dependent on the label distribution. Overall, we argue that diversity is a measure of model fit, in precisely the same sense as bias and variance, but accounting for statistical dependencies between ensemble members. Thus, we should not be maximising diversity as so many works aim to do -- instead, we have a bias/variance/diversity trade-off to manage.
format Preprint
id arxiv_https___arxiv_org_abs_2301_03962
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle A Unified Theory of Diversity in Ensemble Learning
Wood, Danny
Mu, Tingting
Webb, Andrew
Reeve, Henry
Luján, Mikel
Brown, Gavin
Machine Learning
Artificial Intelligence
We present a theory of ensemble diversity, explaining the nature of diversity for a wide range of supervised learning scenarios. This challenge has been referred to as the holy grail of ensemble learning, an open research issue for over 30 years. Our framework reveals that diversity is in fact a hidden dimension in the bias-variance decomposition of the ensemble loss. We prove a family of exact bias-variance-diversity decompositions, for a wide range of losses in both regression and classification, e.g., squared, cross-entropy, and Poisson losses. For losses where an additive bias-variance decomposition is not available (e.g., 0/1 loss) we present an alternative approach: quantifying the effects of diversity, which turn out to be dependent on the label distribution. Overall, we argue that diversity is a measure of model fit, in precisely the same sense as bias and variance, but accounting for statistical dependencies between ensemble members. Thus, we should not be maximising diversity as so many works aim to do -- instead, we have a bias/variance/diversity trade-off to manage.
title A Unified Theory of Diversity in Ensemble Learning
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2301.03962