---
title: "Out-of-Domain Finetuning to Bootstrap Hallucination Detection"
url: https://daily.dev/posts/out-of-domain-finetuning-to-bootstrap-hallucination-detection-ngs7ewldc
source_url: https://eugeneyan.com/writing/finetuning
type: article
source: "Eugene Yan"
published: 2026-05-31T07:40:22.831Z
updated: 2026-05-31T08:22:15.383Z
tags: ["python", "llm"]
reading_time: 10
upvotes: 0
comments: 0
language: en
---

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# Out-of-Domain Finetuning to Bootstrap Hallucination Detection

**[Eugene Yan](https://daily.dev/sources/eugeneyan)** · 10 min read · 0 upvotes · 0 comments

## Summary

Explores using out-of-domain data to bootstrap hallucination detection in LLMs. By pre-finetuning a BART-based NLI model on Wikipedia summaries (USB dataset) before finetuning on the Factual Inconsistency Benchmark (FIB) for news summaries, PR AUC improved from 0.69 to 0.85 — a 23% gain. Recall at threshold 0.8 jumped 25x (0.02 to 0.50) and precision rose 35%. The key insight: even though USB pre-finetuning alone didn't improve FIB performance, it primed the model to learn more effectively from FIB data, demonstrating that transfer learning via sequential finetuning on related open-source datasets can reduce the need for costly in-domain labeled data.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://eugeneyan.com/writing/finetuning>

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Tags: [#python](https://daily.dev/tags/python), [#llm](https://daily.dev/tags/llm)

[View this post on daily.dev](https://daily.dev/posts/out-of-domain-finetuning-to-bootstrap-hallucination-detection-ngs7ewldc)
