This paper provides practical guidance for researchers who are designing and analyzing studies that randomize schools--which comprise three levels of clustering (students in classrooms in schools)--to measure intervention effects on student academic outcomes when information on the middle level (classrooms) is missing. This situation arises…

Inferences that might be made from international educational assessments are discussed, considering issues of popular definition and sampling, assessment exercises, background variables, and statistical analyses. International assessments do tell something about academic achievement, but other approaches may provide more cost-effective information…