Cube root weak convergence of empirical estimators of a density level set

Philippe Berthet, John Einmahl

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Abstract

Given n independent random vectors with common density f on Rd, we study the weak convergence of three empirical-measure based estimators of the convex λ-level set Lλ of f, namely the excess mass set, the minimum volume set and the maximum probability set, all selected from a class of convex sets A that contains Lλ. Since these set-valued estimators approach Lλ, even the formulation of their weak convergence is non-standard. We identify the joint limiting distribution of the symmetric difference of Lλ and each of the three estimators, at rate n−1/3. It turns out that the minimum volume set and the maximum probability set estimators are asymptotically indistinguishable, whereas the excess mass set estimator exhibits "richer" limit behavior. Arguments rely on the boundary local empirical process, its cylinder representation, dimension-free concentration around the boundary of Lλ, and the set-valued argmax of a drifted Wiener process.
Original languageEnglish
Pages (from-to)1423-1446
JournalAnnals of Statistics
Volume50
Issue number3
DOIs
Publication statusPublished - Jun 2022

Keywords

  • Argmax drifted Wiener process
  • cube root asymptotics
  • density level set
  • excess mass
  • local empirical process
  • minimum volume set
  • set-valued estimator

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