Multilevel models are increasingly used in sociology and other social sciences to analyze variation of tie outcomes in egocentrically sampled network data, particularly in studies of social support. Existing research assumes that the personal networks in the data do not overlap (i.e., they do not have actors in common), which makes standard…

International mathematics assessments have established students in East Asia as among the best in the world and their U.S. counterparts as mediocre. What is not clear is why this "achievement gap" exists. The last major study to address this question, Stevenson and Stigler's (1992) "The Learning Gap," was published prior to…