It was published in the journal Compare: A Journal of Comparative and International Education the article Is knowledge capital theory degenerate? PIAAC, PISA, and economic growth by Jeremy Rappleye and Hikaru Komatsu. The authors used data from PIAAC (Programme for the International Assessment of Adult Competencies) , an international comparative study, promoted by the OECD and aimed at evaluating the skills of the adult population aged between 16 and 65, to test the central assumptions of the Theory of Knowledge Capital, understood as an extreme version of Human Capital Theory. While the Human Capital Theory assumes that the skills of adults, including the cognitive ones, affect the economic growth of each country, the Knowledge Capital Theory argues that only cognitive skills determine this growth. The results found by Jeremy Rappleye and Hikaru Komatsu refute the linkage between cognitive levels and GDP growth per capita envisaged by proponents of Knowledge Capital, most notably the OECD and World Bank.