$α$-TCAV: A Unified Framework for Testing with Concept Activation Vectors

Fuente: arXiv
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Autores principales: Schnoor, Ekkehard, Said, Jawher, Tiomoko, Malik, Samek, Wojciech, Jung, Alexander
Formato: Preprint
Publicado: 2026
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author Schnoor, Ekkehard
Said, Jawher
Tiomoko, Malik
Samek, Wojciech
Jung, Alexander
author_facet Schnoor, Ekkehard
Said, Jawher
Tiomoko, Malik
Samek, Wojciech
Jung, Alexander
contents Concept Activation Vectors (CAVs) are a fundamental tool for concept-based explainability in deep learning, yet their practical utility is limited by statistical instability. We analyze the stochastic nature of CAVs and the Testing with CAVs (TCAV) method, deriving the distributions of major CAV classes including PatternCAV, FastCAV, and ridge regression-based CAVs. We then identify a fundamental flaw in the standard TCAV score: its reliance on a discontinuous indicator function induces non-decaying variance in critical regimes. To address this, we introduce $α$-TCAV, a generalized framework that replaces the indicator with a parameterized smooth function, yielding a unified probabilistic formulation that subsumes both TCAV and Multi-TCAV. We characterize the induced distributions of sensitivity scores and different TCAV variants, showing that established state-of-the-art choices lack theoretical justification. We provide principled guidance on tuning the parameter in $α$-TCAV -- either to imitate Multi-TCAV at substantially lower computational cost, or to obtain a calibrated Bayes-optimal probabilistic measure of a concept's influence. Finally, our analysis yields practical recommendations that challenge established routines: most notably, allocating the full sampling budget to a single CAV rather than splitting it across several.
format Preprint
id arxiv_https___arxiv_org_abs_2605_15688
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle $α$-TCAV: A Unified Framework for Testing with Concept Activation Vectors
Schnoor, Ekkehard
Said, Jawher
Tiomoko, Malik
Samek, Wojciech
Jung, Alexander
Machine Learning
Artificial Intelligence
Probability
Concept Activation Vectors (CAVs) are a fundamental tool for concept-based explainability in deep learning, yet their practical utility is limited by statistical instability. We analyze the stochastic nature of CAVs and the Testing with CAVs (TCAV) method, deriving the distributions of major CAV classes including PatternCAV, FastCAV, and ridge regression-based CAVs. We then identify a fundamental flaw in the standard TCAV score: its reliance on a discontinuous indicator function induces non-decaying variance in critical regimes. To address this, we introduce $α$-TCAV, a generalized framework that replaces the indicator with a parameterized smooth function, yielding a unified probabilistic formulation that subsumes both TCAV and Multi-TCAV. We characterize the induced distributions of sensitivity scores and different TCAV variants, showing that established state-of-the-art choices lack theoretical justification. We provide principled guidance on tuning the parameter in $α$-TCAV -- either to imitate Multi-TCAV at substantially lower computational cost, or to obtain a calibrated Bayes-optimal probabilistic measure of a concept's influence. Finally, our analysis yields practical recommendations that challenge established routines: most notably, allocating the full sampling budget to a single CAV rather than splitting it across several.
title $α$-TCAV: A Unified Framework for Testing with Concept Activation Vectors
topic Machine Learning
Artificial Intelligence
Probability
url https://arxiv.org/abs/2605.15688