1. Human capital may also be important for entrepreneurial success in an economy. See, for example, Jens M. Unger, et al. (2011) “Human Capital and Entrepreneurial Success: A Meta-analytical Review”, Journal of Business Venturing, 26: 341–358.
2. Much of the available information across countries of human capital investment is related to educational expenditures or levels of educational attainment. Ideally, one should also include health and training-related investments. However, measuring the latter contributions has proven to be fraught with difficulties and thus a challenge. See the Appendix to this chapter and the discussion in Gang Liu and Barbara Fraumeni (2014) “Human Capital Measurement: A Bird’s Eye View”, chapter 3 in United Nations University (UNU)-International Human Dimensions Programme (IHDP) on Global Environmental Change; and United Nations Environment Programme (UNEP) (2014) Inclusive Wealth Report 2014. Measuring Progress Toward Sustainability. Cambridge: Cambridge University Press, pp. 83–108.
3. Robert J. Barro and Jong Wha Lee (2013) “A New Data Set of Educational Attainment in the World, 1950–2010”, Journal of Development Economics, 104: 184–198.
4. This tradition stems from the Hecksher- Ohlin, or factor proportions, theory of how the comparative advantage of a country’s production, and thus its trade, is determined. Early developments of this theory stressed strongly that the primary factors key to determining the factor intensity of production and trade were the immobile endowments of an economy. For example, see Paul A. Samuelson (1948) “International Trade and the Explanation of Factor Prices”, The Economic Journal, 58: 163–184, p. 164: “The present note attempts to throw light on the matter under the simplifying assumptions most suited to the Ohlin analysis: two regions, say Europe and America, each endowed with different proportions of two perfectly immobile factors of production, say land and labor.” Similarly, Harry G. Johnson (1957) “Factor Endowments, International Trade and Factor Prices”, The Manchester School, 25: 270–283, p. 271 states: “… on the production side, technology and the supply of factors of production in each country are given (the latter implying that factors are immobile between countries).”
5. Adrian Wood (1994) “Give Hecksher and Ohlin a Chance!”, Welt wirtschaftliches Archiv. (Review of World Economy), 130: 20–49, 21–22. Note also that Samuelson (1948), op. cit., in his influential development of the factor proportions (Hecksher-Ohlin) theory of trade considered the “two perfectly immobile factors of production” to be “land and labor” and not capital.