s1: Simple test-time scaling
Authors: name: Niklas Muennighoff; name: Zitong Yang; name: Weijia Shi; name: Xiang Lisa Li; name: Li Fei-Fei; name: Hannaneh Hajishirzi; name: Luke Zettlemoyer; name: Percy Liang; name: Emmanuel Candès; name: Tatsunori Hashimoto
Published: 2025-01-31 18:48:08

Abstract: Test-time scaling is a promising new approach to language modeling that uses
extra test-time compute to improve performance. Recently, OpenAI's o1 model
showed this capability but did not publicly share its methodology, leading to
many replication efforts. We seek the simplest approach to achieve test-time
scaling and strong reasoning performance. First, we curate a small dataset s1K
of 1,000 questions paired with reasoning traces relying on three criteria we
validate through ablations: difficulty, diversity, and quality. Second, we
develop budget forcing to control test-time compute by forcefully terminating
the model's thinking process or lengthening it by appending "Wait" multiple
times to the model's generation when it tries to end. This can lead the model
to double-check its answer, often fixing incorrect reasoning steps. After
supervised finetuning the Qwen2.5-32B-Instruct language model on s1K and
equipping it with budget forcing, our model s1 exceeds o1-preview on
competition math questions by up to 27% (MATH and AIME24). Further, scaling s1
with budget forcing allows extrapolating beyond its performance without
test-time intervention: from 50% to 57% on AIME24. Our model, data, and code
are open-source at https://github.com/simplescaling/s1.