Do LLMs Know When to NOT Answer? Investigating Abstention Abilities of Large Language Models

Fuente: arXiv
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Auteurs principaux: Madhusudhan, Nishanth, Madhusudhan, Sathwik Tejaswi, Yadav, Vikas, Hashemi, Masoud
Format: Preprint
Publié: 2024
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author Madhusudhan, Nishanth
Madhusudhan, Sathwik Tejaswi
Yadav, Vikas
Hashemi, Masoud
author_facet Madhusudhan, Nishanth
Madhusudhan, Sathwik Tejaswi
Yadav, Vikas
Hashemi, Masoud
contents Abstention Ability (AA) is a critical aspect of Large Language Model (LLM) reliability, referring to an LLM's capability to withhold responses when uncertain or lacking a definitive answer, without compromising performance. Although previous studies have attempted to improve AA, they lack a standardised evaluation method and remain unsuitable for black-box models where token prediction probabilities are inaccessible. This makes comparative analysis challenging, especially for state-of-the-art closed-source commercial LLMs. This paper bridges this gap by introducing a black-box evaluation approach and a new dataset, Abstain-QA, crafted to rigorously assess AA across varied question types (answerable and unanswerable), domains (well-represented and under-represented), and task types (fact centric and reasoning). We also propose a new confusion matrix, the ''Answerable-Unanswerable Confusion Matrix'' (AUCM) which serves as the basis for evaluating AA, by offering a structured and precise approach for assessment. Finally, we explore the impact of three prompting strategies-Strict Prompting, Verbal Confidence Thresholding, and Chain-of-Thought (CoT)-on improving AA. Our results indicate that even powerful models like GPT-4, Mixtral 8x22b encounter difficulties with abstention; however, strategic approaches such as Strict prompting and CoT can enhance this capability.
format Preprint
id arxiv_https___arxiv_org_abs_2407_16221
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Do LLMs Know When to NOT Answer? Investigating Abstention Abilities of Large Language Models
Madhusudhan, Nishanth
Madhusudhan, Sathwik Tejaswi
Yadav, Vikas
Hashemi, Masoud
Computation and Language
Abstention Ability (AA) is a critical aspect of Large Language Model (LLM) reliability, referring to an LLM's capability to withhold responses when uncertain or lacking a definitive answer, without compromising performance. Although previous studies have attempted to improve AA, they lack a standardised evaluation method and remain unsuitable for black-box models where token prediction probabilities are inaccessible. This makes comparative analysis challenging, especially for state-of-the-art closed-source commercial LLMs. This paper bridges this gap by introducing a black-box evaluation approach and a new dataset, Abstain-QA, crafted to rigorously assess AA across varied question types (answerable and unanswerable), domains (well-represented and under-represented), and task types (fact centric and reasoning). We also propose a new confusion matrix, the ''Answerable-Unanswerable Confusion Matrix'' (AUCM) which serves as the basis for evaluating AA, by offering a structured and precise approach for assessment. Finally, we explore the impact of three prompting strategies-Strict Prompting, Verbal Confidence Thresholding, and Chain-of-Thought (CoT)-on improving AA. Our results indicate that even powerful models like GPT-4, Mixtral 8x22b encounter difficulties with abstention; however, strategic approaches such as Strict prompting and CoT can enhance this capability.
title Do LLMs Know When to NOT Answer? Investigating Abstention Abilities of Large Language Models
topic Computation and Language
url https://arxiv.org/abs/2407.16221