Sources of rising student debt in the U.S.: College costs, wage inequality, and delinquency
中文摘要
本文考察大学成本上升、工资不平等加剧与拖欠行为对美国学生债务增长的定量影响。本文将大学成本上升与工资不平等加剧作为外生投入，引入一个包含大学入学、学生贷款与拖欠选择的非完备市场世代交叠模型。在基准经济中，1985年至2014年间总学生债务增加3140亿美元，约占美国观察到的本科生学生贷款增幅的64%。大学成本上升是借贷增加的主要驱动因素，而收入风险上升与学生能力下降则导致更高的拖欠率。拖欠率上升显著放大了债务积累：在一个不允许选择拖欠的反事实经济中，债务仅增加1780亿美元。最后，我们表明收入驱动还款（IDR）计划能够大幅缓和债务增长，使债务仅增加1690亿美元。这一效应之所以出现，是因为IDR通过提供更大的还款灵活性降低了拖欠率。
Abstract
This paper examines the quantitative implications of rising college costs, wage inequality, and delinquency for the growth of student debt in the U.S. Rising college costs and wage inequality are introduced as exogenous inputs into an incomplete-markets overlapping-generations model with choices of college attendance, student loans, and delinquency. In the benchmark economy, aggregate student debt rises by $314 billion between 1985 and 2014, accounting for approximately 64 % of the observed rise in undergraduate student loans in the U.S. The rise in college costs is the primary driver of the increased borrowing, while the rise in income risk and the decline in student ability lead to higher delinquency rates. Increasing delinquency significantly amplifies debt accumulation: in a counterfactual economy without the option of becoming delinquent, debt increases by only $178 billion. Finally, we show that income-driven repayment (IDR) plans can substantially moderate debt growth, leading to an increase of only $169 billion. This effect arises because IDR reduces delinquency rates by offering greater repayment flexibility.