4.3.1 Objectives of meta-analysis

The objectives of meta-analysis should be pre-specified in the review protocol. There are different legitimate objectives for a meta-analysis: to improve statistical power to detect a treatment effect, to estimate a summary average effect, to identify subsets of studies (sub-groups) associated with a beneficial effect, and to explore if there are differences in the size or direction of the treatment effect associated with study-specific variables (Normand 1999).