Scaling Laws in Linear Regression: Compute, Parameters, and Data

Fuente: arXiv
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Hauptverfasser: Lin, Licong, Wu, Jingfeng, Kakade, Sham M., Bartlett, Peter L., Lee, Jason D.
Format: Preprint
Veröffentlicht: 2024
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author Lin, Licong
Wu, Jingfeng
Kakade, Sham M.
Bartlett, Peter L.
Lee, Jason D.
author_facet Lin, Licong
Wu, Jingfeng
Kakade, Sham M.
Bartlett, Peter L.
Lee, Jason D.
contents Empirically, large-scale deep learning models often satisfy a neural scaling law: the test error of the trained model improves polynomially as the model size and data size grow. However, conventional wisdom suggests the test error consists of approximation, bias, and variance errors, where the variance error increases with model size. This disagrees with the general form of neural scaling laws, which predict that increasing model size monotonically improves performance. We study the theory of scaling laws in an infinite dimensional linear regression setup. Specifically, we consider a model with $M$ parameters as a linear function of sketched covariates. The model is trained by one-pass stochastic gradient descent (SGD) using $N$ data. Assuming the optimal parameter satisfies a Gaussian prior and the data covariance matrix has a power-law spectrum of degree $a>1$, we show that the reducible part of the test error is $Θ(M^{-(a-1)} + N^{-(a-1)/a})$. The variance error, which increases with $M$, is dominated by the other errors due to the implicit regularization of SGD, thus disappearing from the bound. Our theory is consistent with the empirical neural scaling laws and verified by numerical simulation.
format Preprint
id arxiv_https___arxiv_org_abs_2406_08466
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Scaling Laws in Linear Regression: Compute, Parameters, and Data
Lin, Licong
Wu, Jingfeng
Kakade, Sham M.
Bartlett, Peter L.
Lee, Jason D.
Machine Learning
Artificial Intelligence
Statistics Theory
Empirically, large-scale deep learning models often satisfy a neural scaling law: the test error of the trained model improves polynomially as the model size and data size grow. However, conventional wisdom suggests the test error consists of approximation, bias, and variance errors, where the variance error increases with model size. This disagrees with the general form of neural scaling laws, which predict that increasing model size monotonically improves performance. We study the theory of scaling laws in an infinite dimensional linear regression setup. Specifically, we consider a model with $M$ parameters as a linear function of sketched covariates. The model is trained by one-pass stochastic gradient descent (SGD) using $N$ data. Assuming the optimal parameter satisfies a Gaussian prior and the data covariance matrix has a power-law spectrum of degree $a>1$, we show that the reducible part of the test error is $Θ(M^{-(a-1)} + N^{-(a-1)/a})$. The variance error, which increases with $M$, is dominated by the other errors due to the implicit regularization of SGD, thus disappearing from the bound. Our theory is consistent with the empirical neural scaling laws and verified by numerical simulation.
title Scaling Laws in Linear Regression: Compute, Parameters, and Data
topic Machine Learning
Artificial Intelligence
Statistics Theory
url https://arxiv.org/abs/2406.08466