Yet more surprising was the ordering of countries: by and large, the social and educational homogeneity of countries does not predict homogeneity of student performance. Some small and homogeneous countries—for example, Tunisia and Norway—do have relatively small standard deviations of scores, but many do not. For example, in all three TIMSS surveys, the standard deviation of scores in Japan and Korea—both countries that are socially more homogeneous than the U.S. and that have more homogeneous education systems through the eighth grade—was roughly similar to the U.S. standard deviation.
