“…In contrast to goods production functions, there is not much empirical evidence and no consensus about the determinants of human capital growth, nor about the underlying functional form and parameter values (Bouzahzah, de la Croix, and Docquier 2002). The literature shows a variety of functions, typically including one or two of the following inputs: individual time allocated to education, private expenditures on education by individuals themselves or by their parents, and government expenditures on education (e.g., Lucas 1988, Glomm and Ravikumar 1992, Docquier and Michel 1999, Kaganovich and Zilcha 1999, Bouzahzah, de la Croix, and Docquier 2002, Fougère et al 2009, Arcalean and Schiopu 2010. With two inputs, the adopted functional form is very often Cobb-Douglas (e.g., Glomm and Ravikumar 1992, Docquier and Michel 1999, Kaganovich and Zilcha 1999.…”