Spiking the training data to correct for test set contamination

Fuente: arXiv
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Main Authors: Wei, Johnny Tian-Zheng, Li, Jerry, Godbole, Ameya, Jia, Robin
Format: Preprint
Published: 2026
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_version_ 1866911713810448384
author Wei, Johnny Tian-Zheng
Li, Jerry
Godbole, Ameya
Jia, Robin
author_facet Wei, Johnny Tian-Zheng
Li, Jerry
Godbole, Ameya
Jia, Robin
contents The literature on test set contamination largely focuses on detection, but the correction of contaminated test scores is underexplored. Our core proposal is to spike the training data by intentionally contaminating some test examples at known rates. The spiked examples can then be used to calibrate predictors of model memorization which enable principled statistical correction of inflated test scores. To evaluate different correction estimators, we first present a simulation framework based on the Hubble models. Hubble models come in minimal pairs, where the perturbed model was deliberately contaminated with several test sets, while the standard model was not, serving as the counterfactual and correction target. We consider estimators that use information from a memorization predictor, correctness predictor, or both. In simulation, we establish basic statistical intuitions and show that estimators leveraging memorization and correctness information are better than naive estimation which makes no correction at all. We then instantiate several memorization and correctness predictors, and find that simple predictors such as Platt-scaled membership inference metrics provide good signal for correction. Finally, we examine the practical considerations of spiking. Simple memorization predictors need no more than 10 examples for calibration and often transfer from one dataset to another. Taken together, spiking is a promising solution for test set contamination.
format Preprint
id arxiv_https___arxiv_org_abs_2605_24818
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Spiking the training data to correct for test set contamination
Wei, Johnny Tian-Zheng
Li, Jerry
Godbole, Ameya
Jia, Robin
Methodology
Computation and Language
Machine Learning
The literature on test set contamination largely focuses on detection, but the correction of contaminated test scores is underexplored. Our core proposal is to spike the training data by intentionally contaminating some test examples at known rates. The spiked examples can then be used to calibrate predictors of model memorization which enable principled statistical correction of inflated test scores. To evaluate different correction estimators, we first present a simulation framework based on the Hubble models. Hubble models come in minimal pairs, where the perturbed model was deliberately contaminated with several test sets, while the standard model was not, serving as the counterfactual and correction target. We consider estimators that use information from a memorization predictor, correctness predictor, or both. In simulation, we establish basic statistical intuitions and show that estimators leveraging memorization and correctness information are better than naive estimation which makes no correction at all. We then instantiate several memorization and correctness predictors, and find that simple predictors such as Platt-scaled membership inference metrics provide good signal for correction. Finally, we examine the practical considerations of spiking. Simple memorization predictors need no more than 10 examples for calibration and often transfer from one dataset to another. Taken together, spiking is a promising solution for test set contamination.
title Spiking the training data to correct for test set contamination
topic Methodology
Computation and Language
Machine Learning
url https://arxiv.org/abs/2605.24818