From Cross-Validation to SURE: Asymptotic Risk of Tuned Regularized Estimators
- URL: http://arxiv.org/abs/2603.20388v1
- Date: Fri, 20 Mar 2026 18:05:39 GMT
- Title: From Cross-Validation to SURE: Asymptotic Risk of Tuned Regularized Estimators
- Abstract summary: We derive the risk function of regularized empirical risk minimization estimators tuned by $n$-fold cross-validation (CV)<n>The out-of-sample prediction loss converges in distribution to the squared-error loss (risk function) of shrinkage estimators tuned by Stein's unbiased risk estimate (SURE)
- Score: 0.3058685580689604
- License: http://creativecommons.org/licenses/by-nc-sa/4.0/
- Abstract: We derive the asymptotic risk function of regularized empirical risk minimization (ERM) estimators tuned by $n$-fold cross-validation (CV). The out-of-sample prediction loss of such estimators converges in distribution to the squared-error loss (risk function) of shrinkage estimators in the normal means model, tuned by Stein's unbiased risk estimate (SURE). This risk function provides a more fine-grained picture of predictive performance than uniform bounds on worst-case regret, which are common in learning theory: it quantifies how risk varies with the true parameter. As key intermediate steps, we show that (i) $n$-fold CV converges uniformly to SURE, and (ii) while SURE typically has multiple local minima, its global minimum is generically well separated. Well-separation ensures that uniform convergence of CV to SURE translates into convergence of the tuning parameter chosen by CV to that chosen by SURE.
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