The Distributional Uncertainty of the SHAP score in Explainable Machine Learning

Fuente: arXiv
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Autori principali: Cifuentes, Santiago, Bertossi, Leopoldo, Pardal, Nina, Abriola, Sergio, Martinez, Maria Vanina, Romero, Miguel
Natura: Preprint
Pubblicazione: 2024
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author Cifuentes, Santiago
Bertossi, Leopoldo
Pardal, Nina
Abriola, Sergio
Martinez, Maria Vanina
Romero, Miguel
author_facet Cifuentes, Santiago
Bertossi, Leopoldo
Pardal, Nina
Abriola, Sergio
Martinez, Maria Vanina
Romero, Miguel
contents Attribution scores reflect how important the feature values in an input entity are for the output of a machine learning model. One of the most popular attribution scores is the SHAP score, which is an instantiation of the general Shapley value used in coalition game theory. The definition of this score relies on a probability distribution on the entity population. Since the exact distribution is generally unknown, it needs to be assigned subjectively or be estimated from data, which may lead to misleading feature scores. In this paper, we propose a principled framework for reasoning on SHAP scores under unknown entity population distributions. In our framework, we consider an uncertainty region that contains the potential distributions, and the SHAP score of a feature becomes a function defined over this region. We study the basic problems of finding maxima and minima of this function, which allows us to determine tight ranges for the SHAP scores of all features. In particular, we pinpoint the complexity of these problems, and other related ones, showing them to be NP-complete. Finally, we present experiments on a real-world dataset, showing that our framework may contribute to a more robust feature scoring.
format Preprint
id arxiv_https___arxiv_org_abs_2401_12731
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Distributional Uncertainty of the SHAP score in Explainable Machine Learning
Cifuentes, Santiago
Bertossi, Leopoldo
Pardal, Nina
Abriola, Sergio
Martinez, Maria Vanina
Romero, Miguel
Artificial Intelligence
Machine Learning
Logic in Computer Science
68T37, 68T27
Attribution scores reflect how important the feature values in an input entity are for the output of a machine learning model. One of the most popular attribution scores is the SHAP score, which is an instantiation of the general Shapley value used in coalition game theory. The definition of this score relies on a probability distribution on the entity population. Since the exact distribution is generally unknown, it needs to be assigned subjectively or be estimated from data, which may lead to misleading feature scores. In this paper, we propose a principled framework for reasoning on SHAP scores under unknown entity population distributions. In our framework, we consider an uncertainty region that contains the potential distributions, and the SHAP score of a feature becomes a function defined over this region. We study the basic problems of finding maxima and minima of this function, which allows us to determine tight ranges for the SHAP scores of all features. In particular, we pinpoint the complexity of these problems, and other related ones, showing them to be NP-complete. Finally, we present experiments on a real-world dataset, showing that our framework may contribute to a more robust feature scoring.
title The Distributional Uncertainty of the SHAP score in Explainable Machine Learning
topic Artificial Intelligence
Machine Learning
Logic in Computer Science
68T37, 68T27
url https://arxiv.org/abs/2401.12731