Modified: 2007-01-31
Meta-analytic research focuses on synthesizing the results of several studies that report investigations of one topic. Thus, meta-analysis is the analysis of analyses. Until about 30 years ago, scholars doing meta-analytic research used a qualitative approach. They collected all the relevant research on a topic, studied it thoroughly, and drew conclusions based on their analysis. As one example, Eysenck (1952) reviewed 24 studies on the effectiveness of psychotherapy. He concluded that psychotherapy for non-psychotic disorders was no more effective than no treatment at all.
About 30 years ago researchers began using a quantitative technique called meta-analysis, which was introduced and named by Gene Glass (1976). Using the meta-analytic technique, Smith and Glass (1977) re-examined the question of the effectiveness of psychotherapy. They applied meta-analysis to 475 studies and concluded that about 80 percent of those who receive treatment are improved as compared to the average untreated individual. Because of the Smith and Glass meta-analytic study, social scientists today can recommend psychotherapy with confidence. Meta-analysis is a technique that can be used for any topic that has been investigated quantitatively. It can be applied to both experimental and correlational research.