arXiv:2502.11617cs.LGcs.AI2025-02被引 3

对比了深度学习中点估计与分布估计的性能,发现点估计通常更优。

In-Context Parametric Inference: Point or Distribution Estimators?

  • 在上下文学习中比较最大似然与后验推断两种估计方式
  • 点估计在多数任务上表现优于分布估计,尤其在高维场景
  • 适合关注高效推理的模型开发者和算法研究者

贝叶斯与频率学派是统计估计的两大范式。贝叶斯方法将假设视为随机变量,结合先验并通过贝叶斯定理更新信念;频率学派则假设假设为固定未知量,依赖最大似然等估计器。尽管已有大量研究对比二者,但深度学习中以最大似然为主的点估计占据主导地位,因贝叶斯推断面临后验估计的计算复杂性与近似误差。然而,在摊销估计器(amortized estimators)的场景下,对二者权衡的理解仍不充分:上下文学习器可被训练为通过最大似然或最大后验估计输出点值,或使用归一化流、基于得分的扩散采样器、对角高斯近似等方法输出完整后验分布。为此,本文在从线性模型到浅层神经网络的多种设置中进行了严谨的对比分析,采用稳健评估框架衡量模型在可解析任务上的分布内与分布外泛化能力。实验表明,摊销点估计器普遍优于后验推断,尽管后者在部分低维问题中仍具竞争力,我们进一步探讨了其背后原因。

原文摘要 · Abstract (English)

Bayesian and frequentist inference are two fundamental paradigms in statistical estimation. Bayesian methods treat hypotheses as random variables, incorporating priors and updating beliefs via Bayes' theorem, whereas frequentist methods assume fixed but unknown hypotheses, relying on estimators like maximum likelihood. While extensive research has compared these approaches, the frequentist paradigm of obtaining point estimates has become predominant in deep learning, as Bayesian inference is challenging due to the computational complexity and the approximation gap of posterior estimation methods. However, a good understanding of trade-offs between the two approaches is lacking in the regime of amortized estimators, where in-context learners are trained to estimate either point values via maximum likelihood or maximum a posteriori estimation, or full posteriors using normalizing flows, score-based diffusion samplers, or diagonal Gaussian approximations, conditioned on observations. To help resolve this, we conduct a rigorous comparative analysis spanning diverse problem settings, from linear models to shallow neural networks, with a robust evaluation framework assessing both in-distribution and out-of-distribution generalization on tractable tasks. Our experiments indicate that amortized point estimators generally outperform posterior inference, though the latter remain competitive in some low-dimensional problems, and we further discuss why this might be the case.

统计推断点估计后验推断深度学习

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