The Falling Time Cost of College: Evidence from Half a Century of Time Use Data
利用1961至2003年多个数据集，发现美国全日制大学生每周用于课堂和学习的时间从40小时降至27小时，且下降广泛，难以用学生或学校构成变化解释。
Using multiple data sets from different time periods, we document declines in academic time investment by full-time college students in the United States between 1961 and 2003. Full-time students allocated 40 hours per week toward class and studying in 1961, whereas by 2003, they were investing about 27 hours per week. Declines were extremely broad based and are not easily accounted for by framing effects, work or major choices, or compositional changes in students or schools. We conclude that there have been substantial changes over time in the quantity or manner of human capital production on college campuses. © 2011 The President and Fellows of Harvard College and the Massachusetts Institute of Technology.