斯蒂芬·D·威廉森是艾奥瓦大学（University of Iowa）蒂皮商学院（Tippie College of Business）经济学系金融经济学教授，获“切斯特·A·斯教授”（Chester A. Phillips）荣誉称号，是里士满联邦储备银行（Federal Reserve Bank of Richmond）的客座研究员。他获加拿大金斯顿皇后大学（Queen’s University in Kingston）数学学士和经济学硕士学位，并获威斯康星大学麦迪逊分校（University of Wisconsin-Madison）经济学博士学位。曾任教于皇后大学（Queen's University）和西安大略大学（University of Westem Ontario），并以经济学家的身份供职于明尼阿波利斯联邦储备银行（Federal Reserve Bank of Minneapolis）和加拿大银行（Bank of Canada）。威廉森教授曾是亚特兰大、利夫兰、堪萨斯城和明尼阿波利斯联邦储备银行以及联邦储备银行理事会的客座研究员。他也曾是伦敦经济学院（London School of Economics）、爱丁堡大学（University of Edinburgh）、荷兰蒂尔堡大学（Tilburg University）、新西兰惠灵顿维多利亚大学（Victoria University of Wellington）的长期客座教授。威廉森教授的学术文章发表在多个有名经济学杂志上，包括《美国经济评论》（American Economic Review）、《政治经济学杂志》（Journal of Political Economy）、《经济学季刊》（Quarterly Journal of Economics）、《经济研究评论》（Review of Economic Studies）、《经济理论杂志》（Journal of Economic Theory）和《货币经济学杂志》（Journal of Monetary Economics）。
The Product Approach to Measuring GDP The product approach to NIPA is also called the value-added approach. This is becausethe main principle in the product approach is that GDP is calculated as the sum of valueadded to goods and services in production across all productive units in the economyTo calculate GDP using the product approach, we add the value of all goods and servicesproduced in the economy and then subtract the value of all intermediate goods used inproduction to obtain total value added. If we did not subtract the value of intermediategoods used in production, we would be double-counting. In our example, we do notwant to count the value of the coconuts used in the production of restaurant servicesas part of GDP. In the example, the coconut producer does not use any intermediate goods inproduction, so value added in producing coconuts, which is the coconut producer'stotal revenue, is $20 million. For the restaurant, however, valued added is total revenueminus the value of the coconuts used in production; thus, total value added for therestaurant is $18 million. For government production, we have a problem, because thenational defense services provided by the government are not sold at market prices.Standard practice here is to value national defense services at the cost of the inputs toproduction. Here, the only input to production was labor, so the total value added forthe government is $5.5 million. Total value added, or GDP, therefore, is $43.5 million.The GDP calculation using the product approach is summarized in Table 2.6.
