A meta-analysis is a statistical technique. It involves combining the results of studies that are statistically similar, in order to identify a single conclusion. For example, a researcher may conduct a meta-analysis which examines the effectiveness of a particular cognitive intervention program in individuals with a diagnosis of Mild Cognitive Impairment (MCI). To do this would involve pooling the results of randomised controlled trials which assess the particular intervention program that the researcher is interested in, in participants with MCI.
There are several advantages to conducting meta-analyses. Firstly, when compared to the analysis of a single study, the results of a meta-analysis are statistically stronger. This is due to the increased sample size (i.e. number of participants) and greater variability in the sample (i.e. age, gender, etc.) that typically result from combining studies. Meta-analyses also allow for identification of more accurate estimates of the magnitude of the effect(s) of the treatment being investigated. This information can be helpful in determining how useful an intervention or treatment may be in the wider population.