• Media type: E-Article
  • Title: A Simple Adaptive Estimator of the Integrated Square of a Density
  • Contributor: Giné, Evarist; Nickl, Richard
  • imprint: International Statistics Institute / Bernoulli Society, 2008
  • Published in: Bernoulli
  • Language: English
  • ISSN: 1350-7265
  • Origination:
  • Footnote:
  • Description: <p>Given an i.i.d. sample &lt;tex-math&gt;$X_{1},\ldots ,X_{n}$&lt;/tex-math&gt; with common bounded density f₀ belonging to a Sobolev space of order α over the real line, estimation of the quadratic functional &lt;tex-math&gt;$\int_{{\Bbb R}}f_{0}^{2}(x)\,{\rm d}x$&lt;/tex-math&gt; is considered. It is shown that the simplest kernel-based plug-in estimator &lt;tex-math&gt;${\textstyle\frac{2}{n(n-1)h_{n}}}\sum_{1\leq i&lt;j\leq n}k\left({\textstyle\frac{X_{i}-X_{j}}{h_{n}}}\right)$&lt;/tex-math&gt; is asymptotically efficient if α &gt; 1/4 and rate-optimal if α ≤ 1/4. A data-driven rule to choose the bandwidth &lt;tex-math&gt;$h_{n}$&lt;/tex-math&gt; is then proposed, which does not depend on prior knowledge of α, so that the corresponding estimator is rate-adaptive for α ≤ 1/4 and asymptotically efficient if α &gt; 1/4.</p>
  • Access State: Open Access