Abstract:
BACKGROUND:Meta-analysis typically involves combining the estimates from independent studies in order to estimate a parameter of interest across a population of studies. However, outliers often occur even under the random effects model. The presence of such outliers could substantially alter the conclusions in a meta-analysis. This paper proposes a methodology for identifying and, if desired, downweighting studies that do not appear representative of the population they are thought to represent under the random effects model. METHODS:An outlier is taken as an observation (study result) with an inflated random effect variance. We used the likelihood ratio test statistic as an objective measure for determining whether observations have inflated variance and are therefore considered outliers. A parametric bootstrap procedure was used to obtain the sampling distribution of the likelihood ratio test statistics and to account for multiple testing. Our methods were applied to three illustrative and contrasting meta-analytic data sets. RESULTS:For the three meta-analytic data sets our methods gave robust inferences when the identified outliers were downweighted. CONCLUSIONS:The proposed methodology provides a means to identify and, if desired, downweight outliers in meta-analysis. It does not eliminate them from the analysis however and we consider the proposed approach preferable to simply removing any or all apparently outlying results. We do not however propose that our methods in any way replace or diminish the standard random effects methodology that has proved so useful, rather they are helpful when used in conjunction with the random effects model.
journal_name
BMC Med Res Methodoljournal_title
BMC medical research methodologyauthors
Gumedze FN,Jackson Ddoi
10.1186/1471-2288-11-19subject
Has Abstractpub_date
2011-02-16 00:00:00pages
19issn
1471-2288pii
1471-2288-11-19journal_volume
11pub_type
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journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-4-15
更新日期:2004-06-17 00:00:00
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pub_type: 杂志文章
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pub_type: 杂志文章,评审
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journal_title:BMC medical research methodology
pub_type: 信件,评审
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pub_type: 评论,杂志文章
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