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Study finds Chatbot Arena rankings may overstate differences between Similar models

A new paper from arXiv examines the statistical foundations of Chatbot Arena, the popular leaderboard for large language models. The authors argue that the Bradley-Terry model, which underpins the Arena's rankings, assumes Luce's choice axiom. This axiom posits that the relative odds of choosing one option over another remain constant regardless of other available options. The study suggests…

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Key points

  • Analysis of 1.8 million Arena votes shows Bradley-Terry model underestimates decisiveness between similar models.
  • Votes between model versions were 1.37 times more decisive than the standard statistical model predicted.
  • A four-to-six parameter correction improves vote prediction accuracy but barely changes the leaderboard order.

Analyzing 1.8 million votes from the Arena, the researchers found that votes between near-identical models were more decisive than the Bradley-Terry model predicted. Specifically, votes between versions of one model were 1.37 times as decisive as expected, while votes between different sizes of the same generation were 1.26 times more decisive. This effect persisted across various checks, including different prompt subsets and timing analyses.

The authors propose a correction with only four to six parameters that predicts held-out votes better than the standard model. While this correction improves the accuracy of predicting individual votes, particularly in tie situations, it does not significantly change the overall order of the leaderboard. The findings imply that current rankings may not fully capture the subtle differences between closely related models, though the practical impact on the top-tier ordering remains minimal.

Read the original at arXiv cs.CL · by Soovadeep Bakshi, Apurba Bose, Aishwarya Bose, Sandip Nandi primary sourceOpen source ↗

The headline, key points and digest above were generated by Digest AI's editorial model from the linked sources. Automated summaries can contain errors: the sources are the record. Spotted a mistake? Tell us. Published by Martin K., who runs Digest AI and handles corrections.

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