Meta-Analysis

Meta-analysis is a form of data synthesis that statistically combines the results of primary research studies responding to a given question. It has become an indispensable tool for decision making and advancement of knowledge in a variety of disciplines. This chapter provides an overview of this method, beginning with a brief discussion of systematic reviews – the research methodology that undergirds meta-analysis. The chapter then explores specific components of this approach as it is most widely applied in the literature, including issues related to effect sizes, heterogeneity of study outcomes, scope of the analysis, and quality-control issues to consider when conducting a meta-analysis. A brief overview of new and emerging methods for the synthesis of primary research data is also provided, highlighting different forms of meta-analysis and different approaches for the synthesis of research data. Practical examples are provided as illustrations to clarify and reinforce the concepts presented in this chapter.