Is Denmark a much more educationally mobile society than the U.S.? Comment on Andrade and Thomsen (2018) Intergenerational Educational Mobility in Denmark and the United States

I evaluate Andrade and Thomsen’s (2018) study, which concludes that Denmark is significantly more educationally mobile than the U.S. I make three observations. First, Andrade and Thomsen overstate the difference in educational mobility between Denmark and the U.S. Both in international comparison and compared to differences in intergenerational income mobility, Andrade and Thomsen’s reported country differences in educational mobility are negligible. For example, while income mobility estimates reported in the literature differ by 300–600 percent between the two countries, the corresponding educational mobility estimates that Andrade and Thomsen report differ by 10–20 percent. Second, I provide evidence suggesting that Andrade and Thomsen’s use of crude categorical education measures leads them to overstate these negligible differences. Third, Andrade and Thomsen’s empirical analyses of the U.S. data contain several statistical and data-related flaws, with some of them being so severe that they potentially undermine the credibility of their analyses. In sum, Andrade and Thomsen’s results are perfectly consistent with the existence of a mobility paradox much similar to what Sweden-U.S. comparisons show: While Denmark and the U.S. are dissimilar with respect to income mobility, they are similar with respect to educational mobility. Understanding the nature of this paradox should be a key concern for future mobility research.