Renaissance man meets the pin factory: A theory of diverse specialization under uncertainty.

摘要

The fraction of university students in the US graduating with multiple majors or joint degrees has been increasing for at least the last decade, but this trend has not yet been explained. I demonstrate theoretically that innate ability differences are sufficient to create divergence in observed skill investment patterns across individuals and that changes in uncertainty can contribute to changes in the fraction and types of students who acquire more than one skill before entering the skilled labor force for the first time. I assume that the level and balance of abilities constrain the investment possibilities open to students. I find that only in the presence of significant cost complementarities, in the forms of economies of scale or learning by doing, are the brightest and most balanced students the most likely to acquire two marketable skills. This case occurs when the cost per skill falls sufficiently that the marginal surpluses from skill level and skill diversity become positive for the most balanced individuals, who face the greatest absolute skill cost, while perceived uncertainty is sufficiently high to provide the most generally able individuals with an incentive for acquiring more than one skill. After this theoretical exploration, I consider the abilities and skill investment patterns of a group of recent bachelor's degree recipients from UNC-Chapel Hill. The results of this empirical analysis suggest that abilities at matriculation play a far more important role than financial or other demographic factors in determining skill investments, and that cost complementarities are present in the skill acquisition process. The most generally able students in this sample are the most likely to double major, but neither the most able nor the most balanced make the most diverse undergraduate investment. In combination, the results of these analyses suggest that the fraction of students with a double major has been increasing over time within institutions of higher learning because (1) the mean level of general ability of admitted students has been increasing from year to year, and (2) increased perceived wage uncertainty has encouraged the most able students to diversify their skills by adopting a second major.