Reused evaluation sets exaggerate gains in LLM self-improvement loops

Experiments with prompt-rewriting systems show that repeatedly selecting candidates on small evaluation sets creates large gaps between reported and held-out performance.

Big Tech
Litao Hu · Yutong Tang

Meta · Microsoft

Research Digest··3 min read
Hu and Tang study the winner’s curse in LLM self-improvement: selecting the best-looking rewrite from several candidates whose measured performance contains noise.

The authors model each keep-if-better decision using correlated measurement errors, accounting for candidates that share both an incumbent and evaluation items.

Why this paper

From Microsoft and Meta

In one line

Reusing small evaluation sets in LLM self-improvement loops inflates apparent gains, while held-out evaluation reveals smaller gains and often harmful accepted changes.

What we could check

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Research Digest

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