ABSTRACT
The primary goal of international large-scale assessment studies is to provide countries with comparative data on the outcomes of their school systems. They describe performance levels of students in selected grades or age groups in order to supply benchmarking information to policy makers, researchers, practitioners, and the general public. A central feature of these studies is their multilevel structure (e.g., Raudenbush & Bryk, 2002). This feature is highly relevant for designing and implementing the assessments as well as for analyses of the data. Multilevel issues are omnipresent in international large-scale assessment studies and the number of levels that could be taken into account is particularly large, ranging from the individual student to the larger society.
