ShapShift: Explaining Model Prediction Shifts with Subgroup Conditional Shapley Values

Fuente: arXiv
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Auteurs principaux: Bewley, Tom, Amoukou, Salim I., Albini, Emanuele, Mishra, Saumitra, Veloso, Manuela
Format: Preprint
Publié: 2026
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author Bewley, Tom
Amoukou, Salim I.
Albini, Emanuele
Mishra, Saumitra
Veloso, Manuela
author_facet Bewley, Tom
Amoukou, Salim I.
Albini, Emanuele
Mishra, Saumitra
Veloso, Manuela
contents Changes in input distribution can induce shifts in the average predictions of machine learning models. Such prediction shifts may impact downstream business outcomes (e.g. a bank's loan approval rate), so understanding their causes can be crucial. We propose \ours{}: a Shapley value method for attributing prediction shifts to changes in the conditional probabilities of interpretable subgroups of data, where these subgroups are defined by the structure of decision trees. We initially apply this method to single decision trees, providing exact explanations based on conditional probability changes at split nodes. Next, we extend it to tree ensembles by selecting the most explanatory tree and accounting for residual effects. Finally, we propose a model-agnostic variant using surrogate trees grown with a novel objective function, allowing application to models like neural networks. While exact computation can be intensive, approximation techniques enable practical application. We show that \ours{} provides simple, faithful, and near-complete explanations of prediction shifts across model classes, aiding model monitoring in dynamic environments.
format Preprint
id arxiv_https___arxiv_org_abs_2604_11200
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle ShapShift: Explaining Model Prediction Shifts with Subgroup Conditional Shapley Values
Bewley, Tom
Amoukou, Salim I.
Albini, Emanuele
Mishra, Saumitra
Veloso, Manuela
Machine Learning
Artificial Intelligence
Changes in input distribution can induce shifts in the average predictions of machine learning models. Such prediction shifts may impact downstream business outcomes (e.g. a bank's loan approval rate), so understanding their causes can be crucial. We propose \ours{}: a Shapley value method for attributing prediction shifts to changes in the conditional probabilities of interpretable subgroups of data, where these subgroups are defined by the structure of decision trees. We initially apply this method to single decision trees, providing exact explanations based on conditional probability changes at split nodes. Next, we extend it to tree ensembles by selecting the most explanatory tree and accounting for residual effects. Finally, we propose a model-agnostic variant using surrogate trees grown with a novel objective function, allowing application to models like neural networks. While exact computation can be intensive, approximation techniques enable practical application. We show that \ours{} provides simple, faithful, and near-complete explanations of prediction shifts across model classes, aiding model monitoring in dynamic environments.
title ShapShift: Explaining Model Prediction Shifts with Subgroup Conditional Shapley Values
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2604.11200