ABSTRACT
Many of the principles that apply to meta-analyses are applicable to systematic reviews and it will be useful to read the chapter about systematic reviews prior to reading this chapter.
A meta-analysis is the mathematical sum of the results of more than one primary study, all of which have used similar methods in order to address the same question. Metaanalyses are often presented as the statistical analysis (where appropriate) of a systematic review but may also be studies in their own right. The basic principles that apply to systematic reviews are also relevant to meta-analyses, namely that the studies should include:
• A thorough search of the literature. • Explicit and sound study inclusion/exclusion criteria.
