paper

A scalable estimate of the extra-sample prediction error via approximate leave-one-out

arXiv:1801.10243

Abstract

The paper considers the problem of out-of-sample risk estimation under the high dimensional settings where standard techniques such as -fold cross validation suffer from large biases. Motivated by the low bias of the leave-one-out cross validation (LO) method, we propose a computationally efficient closed-form approximate leave-one-out formula (ALO) for a large class of regularized estimators. Given the regularized estimate, calculating ALO requires minor computational overhead. With minor assumptions about the data generating process, we obtain a finite-sample upper bound for . Our theoretical analysis illustrates that with overwhelming probability, when , where the dimension of the feature vectors may be comparable with or even greater than the number of observations, . Despite the high-dimensionality of the problem, our theoretical results do not require any sparsity assumption on the vector of regression coefficients. Our extensive numerical experiments show that decreases as increase, revealing the excellent finite sample performance of ALO. We further illustrate the usefulness of our proposed out-of-sample risk estimation method by an example of real recordings from spatially sensitive neurons (grid cells) in the medial entorhinal cortex of a rat.

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