Most Cochrane Reviews present comparisons between pairs of interventions (an experimental intervention and a comparator intervention) for a specific condition and in a specific population or setting. However, it is usually the case that several, perhaps even numerous, competing interventions are available for any given condition. People who need to decide between alternative interventions would benefit from a single review that includes all relevant interventions, and presents their comparative effectiveness and potential for harm. Network meta-analysis provides an analysis option for such a review.

Any set of studies that links three or more interventions via direct comparisons forms a network of interventions. In a network of interventions there can be multiple ways to make indirect comparisons between the interventions. These are comparisons that have not been made directly within studies, and they can be estimated using mathematical combinations of the direct intervention effect estimates available. Network meta-analysis combines direct and indirect estimates across a network of interventions in a single analysis.

The Comparing Multiple Interventions Group focuses on (1) the methodology for network meta-analysis in Cochrane Reviews; (2) the methodology of overview of reviews that does not involve network meta-analysis.