Sensitivity analyses should be used to examine whether overall findings are robust to potentially influential decisions.ĩ.3 Study designs and identifying the unit of analysisīox 9.8. The pooled estimate is the outcome of the meta-analysis, and is typically explained using a forest plot (Figs. Many judgements are required in the process of preparing a Cochrane review or meta-analysis. A meta-analysis is a quantitative review, in which the clinical effectiveness is evaluated by calculating the weighted pooled estimate for the interventions in at least two separate studies. Random-effects meta-analyses allow for heterogeneity by assuming that underlying effects follow a normal distribution. Variation across studies (heterogeneity) must be considered, although most Cochrane reviews do not have enough studies to allow the reliable investigation of the reasons for it. A systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies was conducted to assess the association between menopausal hormone therapy and. None of the studies coupled the screening test to disease-modifying intervention. The primary studies were all designed and conducted in the absence of knowledge of the diagnostic effectiveness of the test in the given population. Most meta-analysis methods are variations on a weighted average of the effect estimates from the different studies. The Cochrane review has issues with both the primary studies and their meta-analysis. dichotomous, continuous) that result from measurement of an outcome in an individual study, and to choose suitable effect measures for comparing intervention groups. It is important to be familiar with the type of data (e.g. However, they also have the potential to mislead seriously, particularly if specific study designs, within-study biases, variation across studies, and reporting biases are not carefully considered. Potential advantages of meta-analyses include an increase in power, an improvement in precision, the ability to answer questions not posed by individual studies, and the opportunity to settle controversies arising from conflicting claims. Meta-analysis is the statistical combination of results from two or more separate studies. Chapter 9: Analysing data and undertaking meta-analysesĮditors: Jonathan J Deeks, Julian PT Higgins and Douglas G Altman on behalf of the Cochrane Statistical Methods Group. For the current version, please go to /handbook/current or search for this chapter here. This is an archived version of the Handbook.
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