REVIEW 4 major objections 6 minor 13 references
Small-to-Large Generalization: Data Influences Models Consistently Across Scale
T0 review · 4 major / 6 minor · reviewed 2026-08-07 · deepseek-v4-flash
Pith's one-line read Small models predict how data changes move large language models
desk verdict Solid empirical study of proxy-to-large correlation in LMs, but the 'large-scale' claim rests on a single 760M reference and no seed variance. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The central object is the cross-distribution loss correlation between a small proxy and a larger reference model: the coefficient of determination ($R^2$) between proxy and reference average losses across training-data distributions, computed per test set, and the analogous per-sample $R^2$. That quantity, not proxy accuracy, is what the paper argues carries the transfer: a proxy is useful when its loss ordering across data choices matches the reference's. The same transferability is operationalized in the downstream applications through linear datamodels of the form $\hat{f}_z(D) = \sum_{i\in D} \tau(z)_i$, whose weights are estimated with the TRAK influence-function method at proxy scale and then used to attribute or select data for the large model. The compute gap between proxy and reference (175×–370×) is set by training each model on Chinchilla-optimal token counts, so the paper separates model size from training compute.
What would settle it
Train the same ten training-data distributions at a 7B- or 13B-parameter scale and check whether the loss ordering of the 40M proxy still matches; if the correlation drops substantially relative to the 760M reference, the scale-transfer claim would fail at the scales it is meant to inform.
Extended reading notes
Core claim
The central claim is that, for language models, the effect of changing the training-data distribution on a model's losses is largely scale-invariant: small and large models rank the training distributions in the same order. Concretely, after training models from 40M to 760M parameters on ten distributions (six natural sources and four selection-induced), the authors find that proxy losses correlate with reference losses at $R^2$ around 0.9 on four of six test tasks even at a 175× compute gap, with the small models trained on Chinchilla-optimal token counts. The correlation degrades only at the 370× gap (40M parameters) and only on SQuAD and TriviaQA. The same transferability powers two downstream applications: datamodels (TRAK) computed from a proxy that is 1000× cheaper predict the reference's loss on ImageNet with LDS within 10% of the reference's own datamodels, and DSDM dataset selection using a 125M proxy yields a 760M model that matches selection with the 760M reference on SQuAD and LAMBADA. The paper's summary statement is explicitly qualified: proxy reliability is task-dependent and breaks down at the very smallest scales.
Load-bearing premise
The 760M-parameter reference model is taken to be representative of the large-scale models practitioners actually care about, so the correlation pattern observed between 40M and 760M parameters is assumed to continue to much larger models.
Editorial extensions
If this is right
- Data attribution for a 760M model can be done with a model that uses 1000× less compute, losing at most about 10% LDS on ImageNet relative to attributing with the reference model itself.
- Dataset selection for a 760M model with DSDM is as effective using a 125M proxy as using the 760M model, with no accuracy drop until the proxy is 4× cheaper in training compute.
- Small proxies whose accuracy on a task is at or below random guessing can still have losses that highly correlate with the large reference model on that task, so correlation is not tied to proxy competence on the task.
- The reliability of a proxy depends on the test distribution: per-sample correlation is high on HellaSwag and weak on SQuAD, so proxy validity must be checked per task rather than assumed globally.
- The correlation degrades as the compute gap grows, with the 40M proxy (370× gap) the point of failure on SQuAD and TriviaQA, implying a practical floor on proxy size for given tasks.
Reading between the lines
- If loss ordering transfers across scale as reported, data decisions such as deduplication, curriculum order, and mixture ratios could be screened with small models before spending large-model compute; the paper does not run this experiment but its transferability result makes it plausible.
- The task-dependence of correlation suggests 'data influence' is a direction in model-behavior space rather than a single scalar; practitioners should validate proxy fidelity per downstream task, and methods that adapt proxy scale per task could be more efficient than a single global proxy.
- A natural test of the mechanism is architecture transfer: the same experiment repeated with non-transformer or mixture-of-experts models would show whether the pattern is a property of data-driven learning rather than of transformer loss geometry.
- Because each scale is trained with Chinchilla-optimal tokens, the observed correlation confounds parameter count with training compute; an experiment that fixes parameter count and varies training tokens, or vice versa, would separate the two contributions.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. This paper studies whether changes in the training-data distribution affect small and large language models in the same way. The authors train MPT-family LMs (40M-760M parameters) on 10 training distributions, measure their losses on 6 test sets, and report high R^2 between proxy and 760M-reference losses across distributions (Figures 1-3). They then examine two proxy-model applications: TRAK-based data attribution for ImageNet/CIFAR ResNets (Figures 6-7) and DSDM-based dataset selection for an MPT-760M language model (Figure 8). The main claim is that small proxies are generally faithful substitutes for larger models, with some task- and scale-dependent breakdowns, and the paper recommends small proxies as a practical tool.
Significance. If the result is robust, it is practically significant: it would justify the common but previously unquantified practice of using small proxy models for data attribution and dataset selection at larger scale. The paper's strengths are that it is a direct measurement rather than a derivation, it includes per-sample and counterfactual analyses, and the downstream applications benchmark proxy-based scores against independently trained large models. I do not see circularity in the downstream evaluations, since the final accuracy of the large model is measured on a fresh training run. However, the load-bearing limitation is that the "large" reference is a single 760M model, and all cross-scale correlations are computed over only 10 training distributions with no seed variance or confidence intervals.
major comments (4)
- [Section 2.1 and title/abstract] The title-level claim that data influences models "across scale" is supported only by correlations between 40M-125M proxies and a single 760M reference model. The reference scale is explicitly chosen for compute-budget reasons (Section 2.1), so the paper provides no evidence that the correlation extends to the 1B-100B regime that its practical recommendation targets. This is load-bearing because the contribution is the validation of small-to-large transfer. I do not insist on full-scale training, but the paper should either qualify the title-level claim or add a validation at one larger scale, for example by evaluating a publicly available 1B+ checkpoint on the same training-distribution manipulations.
- [Section 2.2, Figures 1 and 2] All cross-scale correlations are computed over only 10 training distributions, with no error bars, no multiple-seed variance, and no leave-one-distribution-out sensitivity. Moreover, several of the distributions are not independent samples: DSDM, Bot-DsDM, DSIR, and Classifier (Section B.1.1) are algorithm-induced subsets of C4, and the DSDM/Bot-DsDM outcomes are reused from datamodel-based selection. This non-independence can inflate the apparent cross-scale agreement. Please report bootstrap confidence intervals and repeat the analysis after excluding the selection-induced distributions, so the reader can see how much of the central correlation rests on those points.
- [Section 2.3, Figure 3] The claim that proxy models "highly correlate with large-scale models even at random-guessing accuracy" relies on HellaSwag and COPA, but COPA is not listed among the six test distributions in Section 2.1 or in the downstream-dataset list of Section B.1.1. Additionally, the x-axis of Figure 3 is described only as "normalized to show improvement over outputting a random guess," without giving the precise normalization. Without a consistent task list and a clear definition of the normalized accuracy, this specific claim cannot be checked.
- [Section 3.2, Figure 8 and Conclusion] The conclusion that "orders-of-magnitude smaller proxy models can be as effective" is not supported by the language-model dataset-selection experiment, where the proxy sizes range only from 125M to 760M parameters (at most a 6x parameter gap and roughly a 4x compute gap). The vision attribution experiment does probe large compute gaps, but the language selection evidence does not. Please either align the concluding claim with the measured proxy-size range or add a smaller-proxy condition to the dataset-selection experiment.
minor comments (6)
- [Section 5] The conclusion contains a typo: "the the choice of training data distribution." Section 4 also contains "approachs" for "approaches."
- [Figure 1 caption] The caption says the small model trains with "175× less compare" instead of "175× less compute," and the same figure is described in the main text as a 57M proxy while Section B.1.1 specifies MPT-80M.
- [Section 2.1 and Appendix B.1.1] The main text lists TriviaQA among the six test datasets, but the list in Appendix B.1.1 omits TriviaQA; the task lists should be harmonized.
- [Section 2.2 and Appendix B.1.3] The main text refers to a 40M proxy with a 370x compute gap, while Appendix B.1.3 uses an MPT-37M model with 840M tokens; the parameter counts and token counts should be made consistent between the main text and the appendix.
- [Figure 4 caption] The caption states the proxy model is 57M parameters and trains with "around 175× the compute of the 760M reference model," which reads as the wrong direction; it should say "175× less compute."
- [Appendix A.3.2] There is a typo in the text "the quality of the attribution scores" written as "thq quality."
Circularity Check
No circularity: the central correlation claim is a direct measurement, and downstream proxy-model evaluations are benchmarked against external reference-model outcomes.
full rationale
The paper's central claim—that model losses across training data distributions correlate between 40M–760M proxies and a 760M reference—is an empirical measurement reported in Section 2.2 (Figures 1 and 2), not a derivation from fitted parameters; the correlation could have been low and is therefore not true by construction. The downstream data-attribution claim (Section 3.1) computes TRAK attribution scores for proxies of various sizes and evaluates them with the Linear Datamodeling Score against the actual losses of the largest reference model (Eq. 2), an external benchmark that does not assume the proxy scores are correct. Likewise, dataset selection (Section 3.2) trains proxy datamodels, selects data with DSDM, retrains the 760M reference on that selected data, and compares its accuracy to a randomly selected baseline (Figure 8); no fitted proxy quantity is renamed as a prediction. Self-citations to TRAK [PGI+23], DSDM [EFM24], and datamodels [IPE+22] appear as tooling in these pipelines, but their outputs are validated against actual model behavior rather than being used as evidence for the cross-scale correlation itself. The acknowledged limitations—the single 760M reference scale (Section 2.1) and low absolute LDS values (Section 3.1.2)—concern external validity and predictive strength, not circularity.
Assumptions & free parameters
assumptions (5)
- domain assumption The 760M MPT model is representative of the large-model class of interest; observed correlations extrapolate to larger scales.
- domain assumption Loss on downstream test sets is a sufficient measure of model behavior for data influence.
- domain assumption The ten training distributions are representative of the space of data distribution changes.
- domain assumption TRAK's linearized gradient-based datamodel approximation is valid for the studied models.
- domain assumption Chinchilla-optimal token-to-parameter ratios are the correct operating point for comparing models across scale.
Cite this review
Pith. "Pith review of Small-to-Large Generalization: Data Influences Models Consistently Across Scale." pith.science (2026). https://pith.science/paper/3TNI45ZJ
@misc{pith2026250516260,
author = {Pith},
title = {Pith review of: Small-to-Large Generalization: Data Influences Models Consistently Across Scale},
year = {2026},
howpublished = {\url{https://pith.science/paper/3TNI45ZJ}},
note = {Machine review of arXiv:2505.16260}
}
read the original abstract
Choice of training data distribution greatly influences model behavior. Yet, in large-scale settings, precisely characterizing how changes in training data affects predictions is often difficult due to model training costs. Current practice is to instead extrapolate from scaled down, inexpensive-to-train proxy models. However, changes in data do not influence smaller and larger models identically. Therefore, understanding how choice of data affects large-scale models raises the question: how does training data distribution influence model behavior across compute scale? We find that small- and large-scale language model predictions (generally) do highly correlate across choice of training data. Equipped with these findings, we characterize how proxy scale affects effectiveness in two downstream proxy model applications: data attribution and dataset selection.
Figures
Figures from the paper (20 more)
Reference graph
Works this paper leans on
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[1]
The cost to compute the gradients for the training set is 6 pD = 6p · T · n
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[2]
When dealing with a target dataset with ntest examples, this cost is 6p · T · ntest
The cost to compute the gradients for the target example is 6 p. When dealing with a target dataset with ntest examples, this cost is 6p · T · ntest
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[3]
The cost to randomly project the gradients of the training examples is n · k · (2p − 1)
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[4]
The cost to randomly project the gradients of the test examples is ntest · k · (2p − 1)
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[5]
The product Φ⊤Φ requires k2 · (2n − 1) FLOPS
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[6]
The inverse operation (Φ⊤Φ)−1 costs around k3 FLOPS
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[7]
The product (Φ⊤Φ)−1Φ⊤ costs n · k · (2k − 1) FLOPS
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[8]
The final product ϕ(z)⊤(Φ⊤Φ)−1Φ⊤ costs n · (2k − 1) FLOPS for a single target example z, and ntest · n · (2k − 1) for attributing over ntest target examples. The total attribution cost is then the sum of the above terms: Cattrib = (6pT + 4k2 + 2k · p − 2k + 2k · ntest − ntest ) · n (28) + 6p · T · ntest + k · (2p − 1) · ntest − k2 + k3 (29) ≈ (6p · T + 4k...
work page 2019
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multiplier effect
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Reviewed August 7, 2026 · model on record in the stance chip above.
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