Introduction to meta-analysis
As a means to synthesize the results of multiple studies, the chronological development of the meta-analysis method was in parallel to a variety of definitions in the literature. Meta-analysis can be defined in different ways: As a means of summarizing and combining the quantitative results of research or as a method used to reach the quantitative effect size based on individual studies. Metaanalysis uses many quantitative approaches and calculation formulas when compiling multiple research findings. In this sense, no researcher needs to be an expert in all types and calculation formulas for all types of meta-analysis. However, if the researcher lacks familiarity with at least some of the main concepts of metaanalysis, then the correct results may not be obtained. This chapter aims to explain some of the main concepts of meta-analysis. © Springer International Publishing Switzerland 2015.