Methods

Meta-analysis can be understood as a form of survey research in which empirical research reports, rather than people, are surveyed (Lipsey & Wilson, 2001). A sample of research reports is collected and each study is ‘interviewed’ by a coder who translates the appropriate information about its characteristics and quantitative findings via a coding form. The resulting data are then analyzed using special statistical techniques to investigate findings in the selected set of studies. The purpose of meta-analysis, therefore, is to describe a body of empirical literature on a theorized relationship in a structured and quantified analysis. The following section introduces the metaanalytic technique of this study, gives an overview of the literature search and coding procedures for primary data, and summarizes the moderator analysis used to test hypotheses.