Elamur Research
☰
home / papers / 2023 / Let's Verify Step by Step

Let's Verify Step by Step

Written for the Research library (claude-opus-5-5) from the paper text, in our own words: the license "arXiv — non-exclusive licence to distribute" does not allow redistributing the text itself. Original — arxiv.org/pdf/2305.20050v1

Summary

Language models that reason in a chain of thought still make logical slips, and one bad step can ruin a whole solution. The paper asks which kind of feedback produces a more trustworthy reward model for catching these errors. One option is outcome supervision (ORM), which judges only the final answer. The other is process supervision (PRM), which judges every intermediate step. The OpenAI team took GPT-4 models, further trained them on the MathMix math corpus, and had human annotators label each step of generated MATH solutions as positive, negative or neutral. Each reward model then picked the best answer from many sampled solutions. To get more value from labelling, annotators were mostly shown solutions that the current PRM rated highly even though their final answer was wrong. This is a form of active learning. The step-level verifier clearly outperformed the outcome-based one, solving 78.2% of a held-out MATH subset. Controlled smaller-scale experiments showed the same trend. The released PRM800K dataset makes research on step-level feedback much more accessible. The results also suggest that rewarding sound reasoning, not just correct answers, helps both accuracy and alignment.

Key points

  • PRM800K: about 800K human step-level labels covering 75K model-generated solutions to 12K MATH problems. Evaluation uses 500 MATH test problems kept out of training.
  • Best-of-N evaluation: the PRM scores a solution as the product of its per-step correctness probabilities. The best GPT-4-based PRM reaches 78.2% on the MATH subset, clearly ahead of the ORM.
  • Active learning: showing annotators "convincing wrong-answer" solutions made process supervision about 2.6× more data-efficient.
  • Cheaper ablations: small models, pretrained with about 200× less compute, were supervised by the large PRM instead of by humans. This allowed a fair comparison of ORM and PRM without new annotation.
  • Relation to Uesato et al. (2022): that study found the two methods roughly equal on GSM8K. This paper argues the gap appears only with larger amounts of process feedback and on harder problems.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

Fields: Mathematics & statistics

Cited by

1328 papers of our library cite it (of the 140673 whose bibliographies we read); 60 of them have a page here, 1268 not yet.

Cite

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.48550/arxiv.2305.20050 · arXiv 2305.20050

@misc{lightman2023let,
  title = {{Let's Verify Step by Step}},
  author = {Lightman, Hunter and Kosaraju, Vineet and Burda, Yura and Edwards, Harri and Baker, Bowen and Lee, Teddy and Leike, Jan and Schulman, John and Sutskever, Ilya and Cobbe, Karl},
  year = {2023},
  doi = {10.48550/arxiv.2305.20050},
  eprint = {2305.20050},
  archivePrefix = {arXiv},
  url = {https://doi.org/10.48550/arxiv.2305.20050}
}

References

26 references, 13 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

  1. A. Askell, Y. Bai, A. Chen, D. Drain, D. Ganguli, T. Henighan, A. Jones, N. Joseph, B. Mann, N. DasSarma, et al. A general language assistant as a laboratory for alignment. arXiv preprint arXiv:2112.00861, 2021. find our card
  2. S. Bubeck, V. Chandrasekaran, R. Eldan, J. Gehrke, E. Horvitz, E. Kamar, P. Lee, Y. T. Lee, Y. Li, S. Lundberg, et al. Sparks of artificial general intelligence: Early experiments with gpt-4. arXiv preprint arXiv:2303.12712, 2023. find our card
  3. P. F. Christiano, J. Leike, T. Brown, M. Martic, S. Legg, and D. Amodei. Deep reinforcement learning from human preferences. Advances in neural information processing systems, 30, 2017. find
  4. K. Cobbe, V. Kosaraju, M. Bavarian, M. Chen, H. Jun, L. Kaiser, M. Plappert, J. Tworek, J. Hilton, R. Nakano, et al. Training verifiers to solve math word problems. arXiv preprint arXiv:2110.14168, 2021. find our card
  5. A. Cotra. Without specific countermeasures, the easiest path to transformative AI likely leads to AI takeover. https://www.alignmentforum.org/posts/pRkFkzwKZ2zfa3R6H/without-specific-countermeasures-the-easiest-path-to, 2022. ↗
  6. A. Creswell, M. Shanahan, and I. Higgins. Selection-inference: Exploiting large language models for interpretable logical reasoning. arXiv preprint arXiv:2205.09712, 2022. find
  7. T. Everitt, V. Krakovna, L. Orseau, M. Hutter, and S. Legg. Reinforcement learning with a corrupted reward channel. arXiv preprint arXiv:1705.08417, 2017. — [arXiv:1705.08417](https://arxiv.org/abs/1705.08417) find
  8. L. Gao, J. Schulman, and J. Hilton. Scaling laws for reward model overoptimization. arXiv preprint arXiv:2210.10760, 2022. find
  9. D. Hendrycks, C. Burns, S. Kadavath, A. Arora, S. Basart, E. Tang, D. Song, and J. Steinhardt. Measuring mathematical problem solving with the math dataset. arXiv preprint arXiv:2103.03874, 2021. find our card
  10. T. Kojima, S. S. Gu, M. Reid, Y. Matsuo, and Y. Iwasawa. Large language models are zero-shot reasoners. arXiv preprint arXiv:2205.11916, 2022. find our card
  11. A. Lewkowycz, A. Andreassen, D. Dohan, E. Dyer, H. Michalewski, V. Ramasesh, A. Slone, C. Anil, I. Schlag, T. Gutman-Solo, et al. Solving quantitative reasoning problems with language models. arXiv preprint arXiv:2206.14858, 2022. find our card
  12. Y. Li, Z. Lin, S. Zhang, Q. Fu, B. Chen, J.-G. Lou, and W. Chen. On the advance of making language models better reasoners. arXiv preprint arXiv:2206.02336, 2022. — [arXiv:2206.02336](https://arxiv.org/abs/2206.02336) find
  13. J. Maynez, S. Narayan, B. Bohnet, and R. McDonald. On faithfulness and factuality in abstractive summarization. arXiv preprint arXiv:2005.00661, 2020. find
  14. R. Nakano, J. Hilton, S. Balaji, J. Wu, L. Ouyang, C. Kim, C. Hesse, S. Jain, V. Kosaraju, W. Saunders, et al. Webgpt: Browser-assisted question-answering with human feedback. arXiv preprint arXiv:2112.09332, 2021. find our card
  15. E. Nichols, L. Gao, and R. Gomez. Collaborative storytelling with large-scale neural language models. In Proceedings of the 13th ACM SIGGRAPH Conference on Motion, Interaction and Games, pages 1–10, 2020. find
  16. M. Nye, A. J. Andreassen, G. Gur-Ari, H. Michalewski, J. Austin, D. Bieber, D. Dohan, A. Lewkowycz, M. Bosma, D. Luan, et al. Show your work: Scratchpads for intermediate computation with language models. arXiv preprint arXiv:2112.00114, 2021. find our card
  17. OpenAI. Gpt-4 technical report. arXiv preprint arXiv:2303.08774, 2023. find our card
  18. L. Ouyang, J. Wu, X. Jiang, D. Almeida, C. L. Wainwright, P. Mishkin, C. Zhang, S. Agarwal, K. Slama, A. Ray, et al. Training language models to follow instructions with human feedback. arXiv preprint arXiv:2203.02155, 2022. find
  19. J. Shen, Y. Yin, L. Li, L. Shang, X. Jiang, M. Zhang, and Q. Liu. Generate & rank: A multi-task framework for math word problems. arXiv preprint arXiv:2109.03034, 2021. find
  20. N. Stiennon, L. Ouyang, J. Wu, D. Ziegler, R. Lowe, C. Voss, A. Radford, D. Amodei, and P. F. Christiano. Learning to summarize with human feedback. Advances in Neural Information Processing Systems, 33:3008–3021, 2020. find
  21. A. Stuhlmüller and J. Byun. Supervise process, not outcomes. https://ought. org/updates/2022-04-06-process, 2022. find
  22. J. Uesato, N. Kushman, R. Kumar, F. Song, N. Siegel, L. Wang, A. Creswell, G. Irving, and I. Higgins. Solving math word problems with process-and outcome-based feedback. arXiv preprint arXiv:2211.14275, 2022. find our card
  23. X. Wang, J. Wei, D. Schuurmans, Q. Le, E. Chi, and D. Zhou. Self-consistency improves chain of thought reasoning in language models. arXiv preprint arXiv:2203.11171, 2022. find our card
  24. J. Wei, X. Wang, D. Schuurmans, M. Bosma, E. Chi, Q. Le, and D. Zhou. Chain of thought prompting elicits reasoning in large language models. arXiv preprint arXiv:2201.11903, 2022. find our card
  25. E. Zelikman, Y. Wu, J. Mu, and N. Goodman. Star: Bootstrapping reasoning with reasoning. Advances in Neural Information Processing Systems, 35: 15476–15488, 2022. find our card
  26. D. M. Ziegler, N. Stiennon, J. Wu, T. B. Brown, A. Radford, D. Amodei, P. Christiano, and G. Irving. Fine-tuning language models from human preferences. arXiv preprint arXiv:1909.08593, 2019. find