L1-Penalised quantile regression in high-dimensional sparse models

By Alexandre Belloni, Victor Chernozhukov. 2009

435 citations recorded by the source corpus.

We consider median regression and, more generally, a possibly infinite collection of quantile regressions in high-dimensional sparse models. In these models the overall number of regressors $p$ is very large, possibly larger than the sample size $n$, but only $s$ of these regressors have non-zero impact on the conditional quantile of the response variable, where $s$ grows slower than $n$. We consider quantile regression penalized by the $\ell_1$-norm of coefficients ($\ell_1$-QR). First, we show that $\ell_1$-QR is consistent at the rate $\sqrt{s/n} \sqrt{\log p}$. The overall number of regressors $p$ affects the rate only through the $\log p$ factor, thus allowing nearly exponential growth in the number of zero-impact regressors. The rate result holds under relatively weak conditions, requiring that $s/n$ converges to zero at a super-logarithmic speed and that regularization parameter satisfies certain theoretical constraints. Second, we propose a pivotal, data-driven choice of the regularization parameter and show that it satisfies these theoretical constraints. Third, we show that $\ell_1$-QR correctly selects the true minimal model as a valid submodel, when the non-zero coefficients of the true model are well separated from zero. We also show that the number of non-zero coefficients in $\ell_1$-QR is of same stochastic order as $s$. Fourth, we analyze the rate of convergence of a two-step estimator that applies ordinary quantile regression to the selected model. Fifth, we evaluate the performance of $\ell_1$-QR in a Monte-Carlo experiment, and illustrate its use on an international economic growth application.

Subfields: Control and Systems Engineering, Statistics and Probability

View Paper: https://www.semanticscholar.org/paper/b98054f4a8582af49c77e53fcd9e68328ce7c01e

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In Control and Systems Engineering

  1. Victor Chernozhukov
  2. Kengo Kato
  3. Alexandre Belloni
  4. Antonio F. Galvao
  5. Jelena Bradic
  6. Mladen Kolar
  7. Max H. Farrell
  8. Christian Hansen

In Statistics and Probability

  1. Victor Chernozhukov
  2. Alexandre Belloni
  3. Christian Hansen
  4. Jelena Bradic
  5. Stefan Wager
  6. Kengo Kato
  7. Iv'an Fern'andez-Val
  8. Whitney K. Newey

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