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EMNLP 2023

Large Language Models Can Self-Improve

Sample 32 reasoning paths per unlabeled question, keep the ones that agree with the majority answer, fine-tune on them. PaLM-540B rose from 74.4% to 82.1% on GSM8K without any labels.

Breakdown by FDE Interviews · 10 min read · Updated

About the original · 2022
AUTHORS
Huang, Gu, Hou, Wu, Wang, Yu, Han
FROM
Google, University of Illinois Urbana-Champaign
PUBLISHED
Oct 2022 · EMNLP 2023
CITED BY
961Semantic Scholar · Nov 2026
IN THIS BREAKDOWN · 10 SECTIONS

You can read 19% of this breakdown.

01

The paper in one minute

Self-consistency samples many reasoning paths for a question and takes the most common answer. On GSM8K, it lifts PaLM-540B from 56.5% with one chain-of-thought pass to 74.4% with 32. That gap suggests the model can already produce better answers than its single pass shows. This paper trains the gap into the model.

The method has three steps. Take questions from a training set and ignore their answers. For each, sample 32 chain-of-thought paths at temperature 0.7 and find the majority answer. Keep every path that reached that answer, write each in four formats (with chain-of-thought examples, with direct-answer examples, with "Let's think step by step" and no examples, with no examples at all), and fine-tune the model on the result. The authors call the trained model LMSI, Language Model Self-Improved.

Across six tasks (GSM8K, DROP, ARC-Challenge, OpenBookQA, ANLI-A2 and ANLI-A3), every prompting method improved. Self-consistency rose by 1.1 to 7.7 points, and a single greedy pass after training came close to or beat self-consistency before it. A model trained on all six tasks' questions also improved on held-out tasks, most on those similar to the training set. Training on the chain-of-thought formats mattered: direct answers alone kept less than a third of the gain. Generated questions and self-generated prompts also worked, less well.

THE IDEA, VISUALLY
THE LOOP (FIGURE 1) unlabeled training questions sample 32 CoT paths, T = 0.7 majority answer = pseudo-label keep paths that reach it write each in 4 formats fine-tune 10k steps Wrong majorities become wrong labels. In our simulation matched to Table 3, 15.5% of kept paths end in a wrong answer, mostly on low-agreement questions. GSM8K, PALM-540B (TABLE 3) before: 1 CoT pass 56.5% before: 32-path vote 74.4% after: 1 CoT pass 73.5% after: 32-path vote 82.1% One pass after training is within 1 point of voting before it: 1 sample instead of 32. SAME DATA, SMALLER MODELS (TABLE 7) PaLM-8B 5.0% 33.4% PaLM-62B 29.7% 57.4% untrained 540B: 56.5% grey = before, green = trained on the 540B model's votes arXiv 2210.11610, Google and UIUC
For each unlabeled training question, the model samples 32 chain-of-thought paths; the most common answer wins, and every path that reached it becomes training data in four prompt formats. After fine-tuning, one greedy pass on GSM8K (73.5%) nearly matches 32-path voting before training (74.4%), and voting after training reaches 82.1%. The same data lifted PaLM-62B from 29.7% to 57.4%, above the untrained 540B model's 56.5%.
Research notes: the problem, approach and results
+7.7 pts

GSM8K with self-consistency, 74.4% to 82.1%, using training questions but no training answers (Table 3)

73.5%

one greedy chain-of-thought pass after self-training, against 74.4% for 32-path voting before it (Table 3)

15.5%

of kept training paths end in a wrong answer in our simulation matched to the paper's 56.5% and 74.4% (our run)

THE PROBLEM

Improving a large model's reasoning usually needs labeled data, and labeled reasoning traces are expensive. Self-consistency (sampling many reasoning paths and voting) improves accuracy at inference, but costs many samples per question every time.

THE IDEA

Use the model's own majority vote as a pseudo-label: sample 32 chain-of-thought paths per unlabeled question, keep the paths that reach the most common answer, and fine-tune on them in four prompt formats so the model does not overfit one style.

THE RESULT

PaLM-540B improved on all six training tasks without ground-truth labels: GSM8K 74.4% to 82.1%, DROP 78.2% to 83.0%, OpenBookQA 90.0% to 94.4%, ANLI-A3 63.4% to 67.9% under self-consistency. Gains carried to held-out tasks, most on tasks similar to training, and to smaller models trained on the same data.

02

Why it matters to an FDE

It cuts inference cost. If a customer is paying for self-consistency in production, training on the votes can bring one greedy pass close to the voted accuracy: 73.5% against 74.4% on GSM8K, with 1 sample instead of 32. That is the most direct business use of the paper.

It uses data customers have. Most customers have many real questions and few labeled answers. Majority-vote pseudo-labels let you adapt a model to their question distribution with no annotation budget, as long as the model is already right more often than not on many of them.

It repeats the model's mistakes. When the majority is wrong, training teaches the wrong answer more firmly. Keep a labeled sample to measure pseudo-label accuracy, filter on vote confidence, and check that the fine-tuned model does not get more confident on its systematic errors.

It transfers to smaller models. The same self-generated data lifted PaLM-62B above the untrained 540B model on GSM8K, which is the path from an expensive model to a cheaper one.

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  • ◇1 architecture diagram
  • </>1 runnable code experiment
  • ▦2 results tables
  • ?5 interview questions with answers
  1. 03Key takeaways

    The pipeline, why mixed formats, the gains and their limits, distillation and two misreadings

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  2. 04How it works

    Sampling and voting, the four formats, training settings, generated questions and prompts

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  3. 05The numbers that matter

    Table 3 before and after, held-out tasks, formats, generated data, distillation and voting

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  4. 06Try it yourself

    Read the tables for what changed, then simulate what majority-vote labels contain

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  5. 07Where it breaks

    Benchmark questions as inputs, temperature tuned on test data, one model, wrong majorities, slips

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  6. 08Using it on a deployment

    When to self-train, how to filter pseudo-labels, and how to check you did not amplify errors

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  7. 09Interview angles

    Five questions this paper prepares you for, with answer hints

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