LAND: Learning an Adaptive Number of Draws for Bayesian Best-of-N Selection

Koen Oostermeijer, Teryn Jones


Abstract
Best-of-N decoding improves generation quality by sampling multiple candidates and selecting the best, but it allocates equal compute to sources regardless of how much they benefit from additional sampling: the expected benefit is small for sources with low-variance score distributions and potentially much larger for those with high-variance distributions. To address this shortcoming, we propose LAND (Learning an Adaptive Number of Draws), which dynamically allocates samples according to their posterior-predictive marginal value. LAND learns a discrete empirical mixture of source-conditioned score distributions from calibration data, updates its belief about a source as completion scores are observed, and stops sampling when the expected improvement of another draw falls below a shared compute price. Across machine-translation experiments with multiple models and language pairs, LAND achieves better MetricX scores than fixed best-of-N at matched average compute. Conversely, at matched translation quality, LAND requires approximately 20-40\% fewer candidate generations. Adaptive allocation therefore provides a simple way to retain the benefits of best-of-N while substantially improving its compute efficiency.
Anthology ID:
2026.wmt-main.28
Volume:
Proceedings of the Eleventh Conference on Machine Translation
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Barry Haddow, Tom Kocmi, Philipp Koehn, Christof Monz
Venues:
WMT | WS
SIG:
SIGMT
Publisher:
Association for Computational Linguistics
Note:
Pages:
520–529
Language:
URL:
https://aclanthology.org/2026.wmt-main.28/
DOI:
Bibkey:
Cite (ACL):
Koen Oostermeijer and Teryn Jones. 2026. LAND: Learning an Adaptive Number of Draws for Bayesian Best-of-N Selection. In Proceedings of the Eleventh Conference on Machine Translation, pages 520–529, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
LAND: Learning an Adaptive Number of Draws for Bayesian Best-of-N Selection (Oostermeijer & Jones, WMT 2026)
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PDF:
https://aclanthology.org/2026.wmt-main.28.pdf