Using multilevel modeling in large-scale planned variation educational experiments: Improving understanding of intervention effects

The author shows how one can combine a large-scale planned variation experimental design and multilevel analysis to address research questions that go beyond the issue of overall treatment effectiveness. In particular, the design and analysis approach presented here can address the following research questions: how an educational intervention produces its results, for whom the intervention works, and whether the intervention works well across different contexts. The author used data based on a large-scale educational field experiment to describe multilevel models that one can use to address this set of research questions. Important design and analysis considerations are highlighted, especially with regard to assessing the impact of school-level characteristics.