<?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>1139-7632</journal-id>
<journal-title><![CDATA[Pediatría Atención Primaria]]></journal-title>
<abbrev-journal-title><![CDATA[Rev Pediatr Aten Primaria]]></abbrev-journal-title>
<issn>1139-7632</issn>
<publisher>
<publisher-name><![CDATA[Asociación Española de Pediatría de Atención Primaria]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S1139-76322018000300020</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Aspectos metodológicos del metaanálisis (1)]]></article-title>
<article-title xml:lang="en"><![CDATA[Methodological aspects of meta-analysis (1)]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Molina Arias]]></surname>
<given-names><![CDATA[Manuel]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
<xref ref-type="aff" rid="Aaf"/>
<xref ref-type="aff" rid="Ab "/>
<xref ref-type="aff" rid="Af1"/>
<xref ref-type="aff" rid="Aaf"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Hospital Universitario La Paz Servicio de Gastroenterología Pediátrica ]]></institution>
<addr-line><![CDATA[Madrid ]]></addr-line>
<country>España</country>
</aff>
<aff id="A1b">
<institution><![CDATA[,Asociación Española de Pediatría Comité de Pedriatría Basada en la Evidencia ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>España</country>
</aff>
<aff id="A1c">
<institution><![CDATA[,Asociación Española de Pediatría de Atención Primaria  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>España</country>
</aff>
<aff id="A1d">
<institution><![CDATA[,Ciencia sin seso  ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>España</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>09</month>
<year>2018</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>09</month>
<year>2018</year>
</pub-date>
<volume>20</volume>
<numero>79</numero>
<fpage>297</fpage>
<lpage>302</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://scielo.isciii.es/scielo.php?script=sci_arttext&amp;pid=S1139-76322018000300020&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://scielo.isciii.es/scielo.php?script=sci_abstract&amp;pid=S1139-76322018000300020&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://scielo.isciii.es/scielo.php?script=sci_pdf&amp;pid=S1139-76322018000300020&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[El metaanálisis es un resumen de síntesis cuantitativa habitualmente empleado para analizar los resultados de los estudios primarios de una revisión sistemática. Para que sus conclusiones tengan validez, debe aplicarse la metodología de elaboración de forma correcta, prestando especial atención a la realización de la revisión, combinando los estudios de forma adecuada y representando los resultados de forma correcta. Revisaremos de forma detallada los aspectos relacionados con el estudio de heterogeneidad de los estudios primarios y con la detección del sesgo de publicación, aspectos fundamentales para la validez interna del metaanálisis.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[ A meta-analysis is a summary of quantitative synthesis usually used to analyze the results of the primary studies of a systematic review. In order for its conclusions to be valid, its methodology must be applied correctly, paying special attention to carrying out the bibliographical search, combining the studies in an appropriate manner and representing the results correctly. We will review in detail the aspects related to the study of heterogeneity of primary studies and the detection of publication bias, fundamental aspects for the internal validity of meta-analysis.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[Revisión]]></kwd>
<kwd lng="es"><![CDATA[Metaanálisis]]></kwd>
<kwd lng="es"><![CDATA[Sesgo de publicación]]></kwd>
<kwd lng="en"><![CDATA[Review]]></kwd>
<kwd lng="en"><![CDATA[Meta-analysis]]></kwd>
<kwd lng="en"><![CDATA[Publication bias]]></kwd>
</kwd-group>
</article-meta>
</front><back>
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