Scaling LLM Test-Time Compute Optimally Can Be More Effective than Scaling Model Parameters

Snell et al., 2025, Scaling LLM Test-Time Compute Optimally Can Be More Effective than Scaling Model Parameters (The Thirteenth International Conference on Learning Representations (ICLR 2025))

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5.3 Analysis Results: Test-Time Scaling for Search with Verifiers

  1. How did search methods compare as the budget grew?
    Beam search beat best-of-N at small budgets but its advantage faded and reversed at large budgets; lookahead search did worst for its cost. Stronger search over-optimized the PRM, producing repetitive low-information steps or very short solutions.
  2. How does the best search method depend on question difficulty?
    On easy questions beam search degraded with more budget (amplifying the verifier’s spurious features) while best-of-N didn’t; on medium-hard questions beam search consistently won; on the hardest, no method helped much.

Source

  • Charlie Snell, Jaehoon Lee, Kelvin Xu and Aviral Kumar. 2025. Scaling LLM Test-Time Compute Optimally Can Be More Effective than Scaling Model Parameters. In The Thirteenth International Conference on Learning Representations (ICLR 2025). https://arxiv.org/abs/2408.03314