<?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>S0120-17512006000200001</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Comparación de metodologías para el análisis de datos de degradación para trayectorias lineales]]></article-title>
<article-title xml:lang="en"><![CDATA[Comparison between Explicit and Approximate Degradation Data Analysis for Linear Paths]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[YÁÑEZ]]></surname>
<given-names><![CDATA[SERGIO]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[GRANADA]]></surname>
<given-names><![CDATA[RONALD ANDRÉS]]></given-names>
</name>
<xref ref-type="aff" rid="A02"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad Nacional de Colombia Escuela de Estadística ]]></institution>
<addr-line><![CDATA[Medellín ]]></addr-line>
</aff>
<aff id="A02">
<institution><![CDATA[,Universidad Nacional de Colombia Escuela de Estadística ]]></institution>
<addr-line><![CDATA[Medellín ]]></addr-line>
</aff>
<pub-date pub-type="pub">
<day>05</day>
<month>12</month>
<year>2006</year>
</pub-date>
<pub-date pub-type="epub">
<day>05</day>
<month>12</month>
<year>2006</year>
</pub-date>
<volume>29</volume>
<numero>2</numero>
<fpage>133</fpage>
<lpage>151</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_arttext&amp;pid=S0120-17512006000200001&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_abstract&amp;pid=S0120-17512006000200001&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.co/scielo.php?script=sci_pdf&amp;pid=S0120-17512006000200001&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Se usarán conceptos de análisis de degradación en relación con la confiabilidad de un producto. Muchos mecanismos de falla pueden detectarse a través de procesos de degradación. La degradación es una debilidad que eventualmente puede causar la falla. Existen varios métodos de análisis para datos de degradación en confiabilidad. En este artículo se comparan los resultados de la metodología de análisis de degradación explícita y de la metodología de análisis de degradación aproximada. Particularmente se diseña un estudio de simulación para el caso en que las trayectorias de degradación son de tipo lineal, para estudiar qué tan diferentes pueden ser las estimaciones de la función de distribución acumulativa del tiempo de vida F(t) dadas por cada una de las metodologías; se encontró que las estimaciones son competitivas para este caso. Se ilustra con datos sobre vida útil de algunos dispositivos láser tomados de Meeker & Escobar (1998).]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[We use the concepts of degradation analysis as they relate to product reliability. Many failure mechanisms can be traced to an underlying degradation process. Degradation eventually leads to a weakness that can cause failure. There are several methodologies for the analysis of degradation data in reliability. This paper compares the explicit degradation methodology with the approximate degradation analysis. Specifically we perform a simulation study for linear degradation paths to explore the different estimations of the cumulative distribution function F(t) given by each methodology and we find that the two methods are competitive. We illustrate the results with data from a laser life test taken from Meeker & Escobar (1998).]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[teoría de confiabilidad]]></kwd>
<kwd lng="es"><![CDATA[modelo de efectos mixtos]]></kwd>
<kwd lng="es"><![CDATA[simulación]]></kwd>
<kwd lng="en"><![CDATA[Reliability theory]]></kwd>
<kwd lng="en"><![CDATA[Mixed effects model]]></kwd>
<kwd lng="en"><![CDATA[Simulation]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[   <font size="2" face="verdana">      <p><b><font size="4">    <center>Comparaci&oacute;n de metodolog&iacute;as para el an&aacute;lisis de datos de degradaci&oacute;n para trayectorias lineales</center></font></b></p>      <p><b><font size="3">    <center>Comparison between Explicit and Approximate Degradation Data Analysis for Linear Paths</center></font></b></p>      <p>    <center>SERGIO Y&Aacute;&Ntilde;EZ<sup>1</sup> RONALD ANDR&Eacute;S GRANADA<sup>2</sup></center></p>      <p><sup>1</sup>Escuela de Estad&iacute;stica, Universidad Nacional de Colombia, Medell&iacute;n, Profesor. E-mail: <a href="mailto:syanez@unalmed.edu.co">syanez@unalmed.edu.co</a>    <br>  <sup>2</sup>Escuela de Estad&iacute;stica, Universidad Nacional de Colombia, Medell&iacute;n, Instructor Asociado. E-mail: <a href="mailto:ronaldgra@yahoo.com">ronaldgra@yahoo.com</a></p>  <hr size="1">      <p><b>    ]]></body>
<body><![CDATA[<center>Resumen</center></b></p>      <p>Se usar&aacute;n conceptos de an&aacute;lisis de degradaci&oacute;n en relaci&oacute;n con la confiabilidad de un producto. Muchos mecanismos de falla pueden detectarse a trav&eacute;s de procesos de degradaci&oacute;n. La degradaci&oacute;n es una debilidad que eventualmente puede causar la falla. Existen varios m&eacute;todos de an&aacute;lisis para datos de degradaci&oacute;n en confiabilidad. En este art&iacute;culo se comparan los resultados de la metodolog&iacute;a de an&aacute;lisis de degradaci&oacute;n expl&iacute;cita y de la metodolog &iacute;a de an&aacute;lisis de degradaci&oacute;n aproximada. Particularmente se dise&ntilde;a un estudio de simulaci&oacute;n para el caso en que las trayectorias de degradaci&oacute;n son de tipo lineal, para estudiar qu&eacute; tan diferentes pueden ser las estimaciones de la funci&oacute;n de distribuci&oacute;n acumulativa del tiempo de vida F(t) dadas por cada una de las metodolog&iacute;as; se encontr&oacute; que las estimaciones son competitivas para este caso. Se ilustra con datos sobre vida &uacute;til de algunos dispositivos l&aacute;ser tomados de Meeker & Escobar (1998).</p>        <p><b>Palabras clave:</b> teor&iacute;a de confiabilidad, modelo de efectos mixtos, simulaci&oacute;n.</p>  <hr size="1">      <p><b>    <center>Abstract</center></b></p>      <p>We use the concepts of degradation analysis as they relate to product reliability. Many failure mechanisms can be traced to an underlying degradation process. Degradation eventually leads to a weakness that can cause failure. There are several methodologies for the analysis of degradation data in reliability. This paper compares the explicit degradation methodology with the approximate degradation analysis. Specifically we perform a simulation study for linear degradation paths to explore the different estimations of the cumulative distribution function F(t) given by each methodology and we find that the two methods are competitive. We illustrate the results with data from a laser life test taken from Meeker & Escobar (1998).</p>      <p><b>Key words:</b> Reliability theory, Mixed effects model, Simulation.</p>  <hr size="1">      <p>Texto completo disponible en <a href="pdf/rce/v29n2/v29n2a01.pdf">PDF</a></p>  <hr size="1">      <p><b><font size="3">Referencias</font></b></p>      <!-- ref --><p>1. Chao, M. T. (1999),<i> Degradation Analysis and Related Topics: some Thoughts and a Review,</i>  National Science Council, R. O. C. Vol. 23, Taipei, Taiwan.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000022&pid=S0120-1751200600020000100001&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p>2. Granada, R. A. (2004), Modelos y an&aacute;lisis para datos de degradaci&oacute;n, Tesis de maestr&iacute;a en estad&iacute;stica, Universidad Nacional de Colombia, sede Medell&iacute;n.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000023&pid=S0120-1751200600020000100002&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p>3. Lu, C. J. & Meeker, W. Q. 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ISBN 3-900051-07-0. *<a href="http://www.R-project.org">http://www.R-project.org</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000028&pid=S0120-1751200600020000100007&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p>8. Venables, W.&Ntilde;. & Ripley, B. D. (2002), <i>Modern Applied Statistics with S</i>, 4th edn, Springer, New York. *<a href="http://www.stats.ox.ac.uk/pub/MASS4">http://www.stats.ox.ac.uk/pub/MASS4</a>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=000029&pid=S0120-1751200600020000100008&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p>9. Y&aacute;&ntilde;ez, S., Granada, R. A. & Jaramillo, M. 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