Influence Diagnostics in High-dimensional M-estimation: Precise Asymptotics
Summary
A precise asymptotic characterization of leave-one-out influences in high-dimensional M-estimation, where the input dimension d grows proportionally to the sample size n (i.e., n ~ d), is presented. For convex M-estimation under Gaussian design, the study reveals that the marginal distribution of test error influences (IF_i) weakly converges to a limiting measure, sharply characterized as the pushforward of a four-dimensional Gaussian distribution through a non-linear map. Similarly, the empirical distribution of DFBETA metrics (DFBETA_i), which quantify changes in model parameters, concentrates to a limiting two-dimensional Gaussian pushforward. Numerical experiments on logistic regression (d=2000, alpha=2, lambda=0.05) and ridge regression (lambda=0.1) validate these theoretical predictions. The findings indicate that influential samples typically reside close to the decision boundary, providing analytical support for common active learning heuristics, a phenomenon also observed qualitatively in real-world datasets like MNIST and chest X-rays.
Key takeaway
For Machine Learning Engineers developing high-dimensional M-estimators or active learning strategies, understanding sample influence is critical. Your data selection policies should prioritize samples near the decision boundary, as these are analytically shown to be most influential in the n ~ d regime. Be aware that the impact of individual samples on model accuracy is maximal at intermediate sample complexities, suggesting a sweet spot for data informativeness.
Key insights
High-dimensional influences in M-estimation converge to predictable distributions, revealing influential samples cluster near decision boundaries.
Principles
- High-dimensional (n~d) influence depends on full dataset.
- Average influence peaks at intermediate sample complexities.
- Label noise flattens influence distributions.
Method
The paper characterizes influence distributions by deriving self-consistent functional equations for complex-valued resolvents, which define summary statistics (Q^(k), V^(k)) that parameterize Gaussian pushforward maps.
In practice
- Prioritize data points near the decision boundary for active learning.
- Consider sample complexity when assessing data informativeness.
- Evaluate DFBETA for empirical distribution of estimator changes.
Topics
- High-dimensional Statistics
- M-estimation
- Influence Diagnostics
- Leave-one-out Cross-validation
- Active Learning
- Gaussian Design
Code references
Best for: Research Scientist, AI Scientist, Machine Learning Engineer, Data Scientist
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Editorial summary, takeaway, and curation by AIssential. Original article published by stat.ML updates on arXiv.org.