The Implications of Meta‐analysis for Educational Research

Meta‐analysis, as developed over the last few years by Glass and others, is a quantitative method for synthesising research results. Its use is illustrated here by means of examples ranging from irreproachable to dubious. Being simple to use and easily understood, meta‐analysis will undoubtedly become popular and this increasing use may well bring about some notable changes. The well‐controlled, small‐scale experiment is likely to become more important and better use will be made of many existing research reports, reports which can now be dusted off and incorporated into meta‐analyses. Because meta‐analysis focuses on how much difference something makes (the magnitude of an effect) and not on whether or not the difference was statistically significant at a pre‐specified level, its use encourages a more scientific approach to the interpretation of quantitative results. It also offers some hope that we might eventually have a clearer idea of the conditions under which research findings can be generalised. Progress in this direction will require mutual support between quantitative and qualitative research methods.