ABSTRACT
More and more scientific research is published each year. This makes it difficult to keep track of available information, and assess bodies of evidence in their entirety. Meta-analysis is a procedure which can be used to combine the results of previous studies in a quantitative way. Meta-analyses typically synthesize all evidence pertaining to a specific research question, and can guide decision-making.
This chapter provides an introduction into meta-analysis. It covers the motivation behind meta-analytic evidence synthesis, how meta-analysis can be defined, and the historic background of this method. Furthermore, common pitfalls and limitations of meta-analyses are discussed, and how they can be addressed in practice.
Lastly, the chapter presents a brief discussion of crucial steps that have to be fulfilled before a meta-analysis can be performed: the definition of a research question and eligibility criteria; analysis plan specification; pre-registration; study search; as well as data extraction and coding. Best practices during each of these steps are described.
