paper

SLOPE - Adaptive variable selection via convex optimization

arXiv:1407.3824 · doi:10.1214/15-AOAS842

Abstract

We introduce a new estimator for the vector of coefficients in the linear model , where has dimensions with possibly larger than . SLOPE, short for Sorted L-One Penalized Estimation, is the solution to \[\min_{b\in\mathbb{R}^p}\frac{1}{2}\Vert y-Xb\Vert _{\ell_2}^2+λ_1\vert b\vert _{(1)}+λ_2\vert b\vert_{(2)}+\cdots+λ_p\vert b\vert_{(p)},\] where and are the decreasing absolute values of the entries of . This is a convex program and we demonstrate a solution algorithm whose computational complexity is roughly comparable to that of classical procedures such as the Lasso. Here, the regularizer is a sorted norm, which penalizes the regression coefficients according to their rank: the higher the rank - that is, stronger the signal - the larger the penalty. This is similar to the Benjamini and Hochberg [J. Roy. Statist. Soc. Ser. B 57 (1995) 289-300] procedure (BH) which compares more significant -values with more stringent thresholds. One notable choice of the sequence is given by the BH critical values , where and is the quantile of a standard normal distribution. SLOPE aims to provide finite sample guarantees on the selected model; of special interest is the false discovery rate (FDR), defined as the expected proportion of irrelevant regressors among all selected predictors. Under orthogonal designs, SLOPE with provably controls FDR at level . Moreover, it also appears to have appreciable inferential properties under more general designs while having substantial power, as demonstrated in a series of experiments running on both simulated and real data.

Published at http://dx.doi.org/10.1214/15-AOAS842 in the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org)

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