Meta-analysis is the practice of statistically summarizing empirical findings from different studies, reaching generalizations about the obtained results. Thus, "meta-analysis" literally refers to analysis of analyses. Meta-analysis, a term coined by Glass (1976), is also known as research synthesis and quantitative reviewing. Because progress within any scientific field has always hinged on cumulating empirical evidence about phenomena in an orderly and accurate fashion, reviews of studies have historically proved extremely influential (e.g., Mazela and Malin 1977). With the exponential growth in the numbers of studies available on a given social scientific topic, the need for these reviews has increased proportionally, meaning that reviews are potentially even more important each day. The empirical evidence, consisting of multiple studies examining a phenomenon, exists as a literature on the topic. Although new studies rarely replicate earlier studies without changing or adding new features, many studies can be described as conceptual replications that...