<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0120-1751</journal-id>
<journal-title><![CDATA[Revista Colombiana de Estadística]]></journal-title>
<abbrev-journal-title><![CDATA[Rev.Colomb.Estad.]]></abbrev-journal-title>
<issn>0120-1751</issn>
<publisher>
<publisher-name><![CDATA[Departamento de Estadística - Universidad Nacional de Colombia.]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0120-17512005000200008</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Métodos numéricos para la estimación de parámetros en regresión cuantílica]]></article-title>
<article-title xml:lang="en"><![CDATA[Numerical Methods to Estimate Parameters in Quantile Regression]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[MORA ESCOBAR]]></surname>
<given-names><![CDATA[HÉCTOR MANUEL]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad Nacional de Colombia Departamento de Matemáticas ]]></institution>
<addr-line><![CDATA[Bogotá ]]></addr-line>
</aff>
<pub-date pub-type="pub">
<day>05</day>
<month>12</month>
<year>2005</year>
</pub-date>
<pub-date pub-type="epub">
<day>05</day>
<month>12</month>
<year>2005</year>
</pub-date>
<volume>28</volume>
<numero>2</numero>
<fpage>221</fpage>
<lpage>231</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_arttext&amp;pid=S0120-17512005000200008&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_abstract&amp;pid=S0120-17512005000200008&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_pdf&amp;pid=S0120-17512005000200008&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[La regresión cuantílica es un problema de optimización convexa no diferenciable. Se examinan las ventajas y desventajas con relación a la necesidad de recursos de memoria y tiempo de cálculo de tres métodos clásicos de solución: dos de optimización lineal y el método de planos de corte.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[Quantile regression is a nondifferentiable convex optimization problem. We compare three classical numerical methods, two of them based on linear optimization, and the cutting plane method. We compare them by their re quired memory and computing time.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[regresión cuantílica]]></kwd>
<kwd lng="es"><![CDATA[optimización lineal]]></kwd>
<kwd lng="es"><![CDATA[optimización no diferenciable]]></kwd>
<kwd lng="es"><![CDATA[planos de corte]]></kwd>
<kwd lng="en"><![CDATA[quantile regression]]></kwd>
<kwd lng="en"><![CDATA[linear programming]]></kwd>
<kwd lng="en"><![CDATA[nondifferentiable optimization]]></kwd>
<kwd lng="en"><![CDATA[cutting planes]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[   <font size="2" face="verdana">        <p>    <center><b><font size="4">M&eacute;todos num&eacute;ricos para la estimaci&oacute;n de  par&aacute;metros en regresi&oacute;n cuant&iacute;lica</font></b></center></p>        <p>    <center><b><font size="3">Numerical Methods to Estimate Parameters in Quantile Regression</font></b></center></p>        <p>    <center>H&Eacute;CTOR MANUEL MORA ESCOBAR<sup>1</sup></center></p>        <p><sup>1</sup>Departamento de Matem&aacute;ticas, Universidad Nacional de Colombia, Bogot&aacute;, E-mail: <a href="mailto:hmmorae@unal.edu.co">hmmorae@unal.edu.co</a></p>    <hr size="1">        <p>    <center><b>Resumen</b></center></p>        ]]></body>
<body><![CDATA[<p>La regresi&oacute;n cuant&iacute;lica es un problema de optimizaci&oacute;n convexa no diferenciable. Se examinan las ventajas y desventajas con relaci&oacute;n a la necesidad  de recursos de memoria y tiempo de c&aacute;lculo de tres m&eacute;todos cl&aacute;sicos de soluci&oacute;n: dos de optimizaci&oacute;n lineal y el m&eacute;todo de planos de corte.</p>        <p><b><i>Palabras Clave:</i></b> regresi&oacute;n cuant&iacute;lica, optimizaci&oacute;n lineal, optimizaci&oacute;n no  diferenciable, planos de corte.</p>    <hr size="1">        <p>    <center><b>Abstract</b></center></p>        <p>Quantile regression is a nondifferentiable convex optimization problem.  We compare three classical numerical methods, two of them based on linear  optimization, and the cutting plane method. We compare them by their re  quired memory and computing time.</p>        <p><b><i>Keywords:</i></b> quantile regression, linear programming, nondifferentiable optimization, cutting planes.</p>    <hr size="1">        <p>Texto completo disponible en <a href="pdf/rce/v28n2/v28n2a08.pdf">PDF</a></p>    <hr size="1">        <p><b><font size="3">Referencias</font></b></p>        <!-- ref --><p>1. Cade, B. &amp; Noon, B. (2003), &quot;A Gentle Introduction to Quantile Regression for  Ecologists&quot;, <i>Frontiers in Ecology and the Environment</i> <b>1</b>(8), 412-420.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000021&pid=S0120-1751200500020000800001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p>2. Cheney, E. &amp; Goldstein, A. 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