human capital is directly useful in the production process.More explicitly, human capital increases a worker’s productivity in all tasks,though possibly differentially in different tasks, organizations, and situations.In this view, although the role of human capital in the production
process may be quite complex, there is a sense in which we can think of it asrepresented (representable) by a unidimensional object, such as the stock Lectures in Labor Economics of knowledge or skills, h, and this stock is directly part of the production function.