Introduction

In research, studies are conducted to try to answer questions about the clinical effectiveness of a treatment or intervention. These studies will have asked whether, for example, does treatment A provide significant benefits over treatment B in a particular group of people? We can use a meta-analysis to combine the results together to get on overall impression about what the results from all of the studies are saying and to get a single pooled result of how much the treatment is beneficial. Meta-analysis does not simply involve averaging the results of the individual studies, but requires a statistical method which combines the results whilst taking into account the sizes of the studies.