Variation in educational outcomes and policies across countries and of schools within countries

"This study examines the variation in educational outcomes across and within countries using the TIMSS mathematics tests. It documents the wide cross-country variation in the level and dispersion of test scores. Countries with the highest test scores are those with the least inequality in scores, which suggests a "virtuous" equity-efficiency trade-off in improving educational outcomes. Analyzing the association of gender, immigrant status, and family background factors with scores, we find large cross-country differences in the relation between those factors and scores"--National Bureau of Economic Research web site