Select or Project? Evaluating Lower-dimensional Vectors for LLM Training Data Explanations

Fuente: arXiv
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Auteurs principaux: Hinterleitner, Lukas, Schoenegger, Loris, Roth, Benjamin
Format: Preprint
Publié: 2026
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author Hinterleitner, Lukas
Schoenegger, Loris
Roth, Benjamin
author_facet Hinterleitner, Lukas
Schoenegger, Loris
Roth, Benjamin
contents Gradient-based methods for instance-based explanation for large language models (LLMs) are hindered by the immense dimensionality of model gradients. In practice, influence estimation is restricted to a subset of model parameters to make computation tractable, but this subset is often chosen ad hoc and rarely justified by systematic evaluation. This paper investigates if it is better to create low-dimensional representations by selecting a small, architecturally informed subset of model components or by projecting the full gradients into a lower-dimensional space. Using a novel benchmark, we show that a greedily selected subset of components captures the information about training data influence needed for a retrieval task more effectively than either the full gradient or random projection. We further find that this approach is more computationally efficient than random projection, demonstrating that targeted component selection is a practical strategy for making instance-based explanations of large models more computationally feasible.
format Preprint
id arxiv_https___arxiv_org_abs_2601_16651
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Select or Project? Evaluating Lower-dimensional Vectors for LLM Training Data Explanations
Hinterleitner, Lukas
Schoenegger, Loris
Roth, Benjamin
Computation and Language
I.2.7
Gradient-based methods for instance-based explanation for large language models (LLMs) are hindered by the immense dimensionality of model gradients. In practice, influence estimation is restricted to a subset of model parameters to make computation tractable, but this subset is often chosen ad hoc and rarely justified by systematic evaluation. This paper investigates if it is better to create low-dimensional representations by selecting a small, architecturally informed subset of model components or by projecting the full gradients into a lower-dimensional space. Using a novel benchmark, we show that a greedily selected subset of components captures the information about training data influence needed for a retrieval task more effectively than either the full gradient or random projection. We further find that this approach is more computationally efficient than random projection, demonstrating that targeted component selection is a practical strategy for making instance-based explanations of large models more computationally feasible.
title Select or Project? Evaluating Lower-dimensional Vectors for LLM Training Data Explanations
topic Computation and Language
I.2.7
url https://arxiv.org/abs/2601.16651