PrAM: Offline Checkpoint Selection for Post-Hoc Training Data Attribution

Stephanie Schoch, Sidhya Pathak, Yangfeng Ji


Abstract
Training data attribution scores how training examples affect downstream model performance. For models released with many intermediate checkpoints, attribution can be computed along the saved training trajectory, but evaluating every checkpoint is often prohibitively expensive. We introduce PrAM (Probe-based Attribution Mass), a post-hoc offline checkpoint selector for training data attribution. PrAM runs a small attribution probe at every checkpoint, selects checkpoints with high absolute attribution mass, and runs full attribution only on that subset. Across Pythia-14M, 70M, and 160M, PrAM closely matches a full attribution-pool reference and outperforms heuristic rules based on recency, spacing, learning rate, and validation loss. Beyond rank correlation, PrAM preserves the domain-by-target attribution tables and ranked training examples produced by full saved-checkpoint attribution, enabling scalable post-hoc analyses of checkpointed model releases. We support this with application-based analyses scaling to 410M and 1B parameter models.
Anthology ID:
2026.findings-emnlp.1521
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
32387–32400
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1521/
DOI:
Bibkey:
Cite (ACL):
Stephanie Schoch, Sidhya Pathak, and Yangfeng Ji. 2026. PrAM: Offline Checkpoint Selection for Post-Hoc Training Data Attribution. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 32387–32400, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
PrAM: Offline Checkpoint Selection for Post-Hoc Training Data Attribution (Schoch et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1521.pdf