Issues in classification in meta-analysis in substance abuse prevention research.

Meta-analysis as a method holds great promise for allowing fields of research to accomplish synthesis and integration of findings. This goal must be compared to experimental research, which is inherently reductionistic in its approach. Because of this divergence in methods and implicit goals, meta-analysts are often faced with a need to reconceptualize original research in order to fit it into a method that allows comparison. The authors have identified two such issues (classification of variables and classification of correlational results) that will pose continued dilemmas for meta-analysts.