Multilevel Models

This special issue on multilevel models includes articles that examine the analysis of community-based interventions on drug and alcohol use and the application of MLM to address design and statistical issues in the evaluation of large-scale, multi-site intervention programs. Both these articles have didactic elements and are laudatory in their clarity of presenting difficult concepts to beginning audiences.The next two articles deal with developmental and longitudinal data analyses that focus on addressing issues in developmental psychology and a broader class of statistical models. The final two articles are highly innovative applications of the MLM. They consider the evaluation of mediated effects in a multilevel context and examples of MLM in a psychiatric context that addresses several challenging statistical problems in MLM analysis. Since mediation is fundamental to science, this is a critically important contribution to the MLM literature.