N.格雷戈里·曼昆（N.Gregory Mankiw），哈佛大学经济学教授。作为学生，他曾在普林斯顿大学和麻省理工学院学习经济学；作为教师，他讲授过宏观经济学、微观经济学、统计学和经济学原理。多年前他甚至还在长滩岛当过一个夏季的帆船运动教练。曼昆教授是一位高产的学者和一位学术与政治争论的经常参与者。他的著作发表在《美国经济评论》（American Economic Review）、《政治经济学杂志》（Journal of Political Economy）和《经济学季刊》（Quarterly Journal of Economics）等学术杂志，以及《纽约时报》（The New YorkTimes）、《金融时报》（The Financial Times）、《华尔街日报》（The Wall Street Journal）和《财富》（Fortune）等热门报刊上。他也是最畅销的中级经济学教科书《宏观经济学》（WorthPublishers出版）的作者。除了教学、研究和写作之外，曼昆教授还是美国国家经济研究局的合作研究人员、波士顿联邦储备银行和国会预算办公室的顾问，以及ETS考试研发委员会下设的经济学高级水平考试委员会成员。从2003年到2005年，他担任总统经济顾问委员会主席。
One government program that increases the amount of frictional unemployment, without intending to do so, is unemployment insurance. This program is designed to offer workers partial protection against job loss. The unemployed who quit their jobs, were fired for cause, or just entered the labor force are not eligible. Benefits are paid only to the unemployed who were laid off because their previous employers no longer needed their skills. Although the terms of the program vary over time and across states, a typical American worker covered by unemployment insurance receives 50 percent of his or her former wages for 26 weeks.
While unemployment insurance reduces the hardship of unemployment, it also increases the amount of unemployment. The explanation is based on one of the Ten Principles of Economics in Chapter 1: People respond to incentives. Because unemployment benefits stop when a worker takes a new job, the unemployed devote less effort to job search and are more likely to turn down unattractive job offers. In addition, because unemployment insurance makes unemployment less onerous, workers are less likely to seek guarantees of job security when they negotiate with employers over the terms of employment.