基于国际贸易数据测算港口效率的新方法【外文翻译】.doc

1、 外文翻译 原文 New Measures Of Port Efficiency Using International Trade Data Material Source: http:/www.nber.org/papers/w1205 Author: Bruce A.Blonigen; Wesley W.Wilson As the clearinghouses for a major portion of the worlds rapidly increasing international trade flows,ocean ports and the efficiency with

2、which they process cargo have become an ever more important topic. Yet, there exist very little data that allows one to compare port efficiency measures of any kind across ports and, especially, over time. This paper provides a new statistical method of uncovering port efficiency measures using U.S.

3、 Census data on imports into U.S. ports. Unlike previous measures, this studys methodology can provide such estimates for a much broader sample of countries and years with little cost. Thus, such data can be used by future researchers to examine a myriad of new issues, including the evolution of por

4、t efficiencies over time and its effects on international trade flows and country-level growth. 1、 Introduction Despite the obvious significance of port efficiency, consistent and comparable measurement of such efficiencies is a daunting task. A myriad of factors contribute to port efficiency. Some

5、of the more obvious factors include dock facilities, connections to rail and trucking lines, harbor characteristics (including channel depth and ocean/tidal movements), time to clear customs, and labor relations. However, both consistent data and methods that allow construction of a measure or index

6、 that allows comparisons across ports are not currently available. The literature is not devoid of attempts to measure port efficiency. One common methodology is through the use of surveys. A recent indicator of port efficiency has been constructed from annual firm-level surveys for the years 1995 t

7、hrough 2000 and reported in the Global Competitiveness Report. These surveys ask firms to rank countries port efficiency from 1 to 7, where 1 indicates that the firm strongly disagrees with the statement “Port facilities and inland waterways are extensive and efficient”, whereas 7 indicates the firm

8、 strongly agrees with the statement. Other studies have used these measures and found that the measures have a strong and significant effect on trade. (Clark et al., 2004, and Wilson et al., 2004) Similarly, Sanchez et al. (2003) use survey data on port efficiency to examine transports costs to Lati

9、n American ports and find that such measures are substantial components of these transport costs and have an impact on trade flows that is similar in magnitude to that of distance. 2、 DATA ACE has also developed a preliminary databank containing port-to-port nautical miles. There are 375 different U

10、S ports in these data which connect to 1789 different domestic and foreign ports. This data set is used to construct the distance (Distij) variable. Merging these distance data into the trade data was problematic since the files did not have common U.S. port codes. The authors developed a correspond

11、ence between the two datasets for these U.S. port codes in order to merge the data. The combined database contains millions of observations, where the unit of observation is a U.S. port, foreign port, a six-digit HS product code and year. Such a large data set presents some computation difficulties.

12、 To mitigate this, we first limit our sample to the top 100 foreign ports by import volume which covers over 81% of all U.S. import activity. Second, we estimated our model for each year, rather than the full sample. Yearly samples had hundreds of thousands of observations and each required over 10

13、hours of computation time on a Linux machine with 8 Gigabytes of RAM using the statistical package, STATA. 3、 RESULTS AND PORT EFFICIENCY ESTIMATES Before focusing on the estimates for the port fixed effects (our measures of port efficiencies), a short discussion of the overall fit and efficacy of t

14、he model is provided. The fit of the model to the data is quite high and stable across years, with R2 statistics ranging from 0.90 to 0.92, indicating that our control variables explain 90% (or more) of the variation in import charges. F-statistics confirm the statistical significance for each of ou

15、r sets of fixed effects at the 1% significance level. 4、 Estimated Port Efficiency Measures （ 1） U.S. Port Efficiencies Measures The model estimated for our results in Table 1 also includes sets of fixed effects for U.S. ports, foreign ports, and 6-digit HTS products. Each of these sets of fixed eff

16、ects is jointly statistically different from zero at the 1% significance level in all regressions. ports across all years in our sample and ranks them from most efficient to least efficient port. These port fixed effects coefficients provide estimates of a ports impact on import charges that are ind

17、ependent from other variables included in our regression. The inclusion of product fixed effects in our regression, for example, means that the port fixed effects should be free of bias from differences in the mix of products a port handles. The lower (or more negative) the coefficient, the lower th

18、e U.S. ports effects on import charges all other variables held constant and, thus, the more efficient the port. An examination of the U.S. port fixed effects estimates reveals that many of the Gulf Coast and West Coast ports rank in the upper half of the list, with Gulfport, Mississippi topping the

19、 list with a coefficient of -0.087, indicating import charges average roughly 8% less than the Port of Oakland. The island ports of Honolulu, Hawaii and San Juan are essentially outliers at the bottom of the list in terms of efficiency with coefficients of 0.349 and 0.609, respectively. Overall, the

20、re is a significant range of estimated port efficiencies. Only 15 of the 50 ports are within 0.05 of the Port of Oakland; that is, within roughly 5% of the Port of Oaklands impact on import charges. The average port has a fixed effect around 0.08 with a standard deviation for the sample around 0.11.

21、 （ 2） Foreign Port Efficiencies Measures Analogous to the estimated U.S. port fixed effects, the estimated foreign port fixedeffects provide measures of foreign port efficiencies, where the smaller (or more negative) the coefficient, the more efficient the port relative to the port we exclude from o

22、ur foreign port set Rotterdam, the Netherlands. 5、 CONCLUSION This study provides new measures of ocean port efficiencies through simple statisticaltools using U.S. data on import flows from 1991 through 2003. Unlike previous measures using surveys, DEA, or production/cost function estimation, this

23、studys methodology can provide such estimates for a much broader sample of countries and years with little cost. It also has the flexibility to quickly provide port efficiency comparisons on a commodity-by-commodity basis (e.g., which U.S. ports are more efficient at handling steel products). The co

24、stliness and strong data requirements of other methodologies is likely why MARAD was unable to identify or provide any port efficiency comparison in a recent Congressional request. Beyond the importantrole of informing policy makers, the readily-available measures of port efficiency can used by futu

25、re researchers to examine a myriad of new issues, including the evolution of port efficiencies over time and its effects on international trade flows and country-level growth. 译文 基于国际贸易数据测算港口效率的新方法 资料来源 : http:/www.nber.org/papers/w1205 作者： Bruce A.Blonigen; Wesley W.Wilson 作为票据交换，成为世界提高国际贸易流动以及海洋港口

26、和他们货物进程的效率的一个主要部分，成为了一个比曾经更重要的一个主题。并且，随着时间的推移，这里存在很少的数据 允许一个比较港口装卸效率措施在所有种类当中横跨港口。这篇论文提供了一个新揭露的统计方法关于港口装卸效率措施落实到在进口美国人口普查数据到美国各港口。不像以前的措施，本研究的方法论能对更宽广的国家样本和多年没有花费作出评估。从而，这样的数据基准被未来研究者在检查新问题时所使用，包括随着时间推移的港口演化效率，它将影响国际贸易流动和国家等级的发展。 1、简介 尽管港口装卸效率的意义明显，一贯的，并且对比如此的测量效率的措施是一个艰巨的任务。一万个因素影响着港口装卸效率。一些更明显的因素包

27、括码头设施，连接轨和卡车 线，海港特征（包括河底深度，海洋 /潮汐的运动），时间通关和劳动关系。然而，两者都一贯的数据基准和方法，允许一个的施工测量指标，允许对照横跨港口不是目前可用的。 文学不是毫无尝试地去估量港口装卸效率，其中之一普通的方法论是通过利用概观。港口装卸效率一个最近的指标已经从 1995年的年度企业概观到 2000年了，并且在全球竞争性报告中得以报道出来。这些概观研究要求企业对于国家港口装卸效率从 1 到 7， 1 表明该公司非常不同意而发表声明“港口设施和内陆水道的范围和效率”，而 7 表明该公司非常同意声明。其他的理论研究使用了这些 措施并且发现这些措施对于贸易行业有强烈的

28、影响力。（克拉克以及其他人， 2004，威尔逊以及其他人， 2004）同样地，桑切斯以及其他人， 2003 在港口装卸效率上使用这些调查数据对拉丁美洲港口的运输费用进行检查，发现这些措施是这些运输成本的坚实的元件并且类似的在大小和距离上对贸易流动有影响。 2、数据 ACE 也开发了一个初级的措施数据库，包含可编程的点对点海里，并且在这些数据中有 375 个不同的美国港口与 1789 个不同的国内和国外港口连接着。这些数据集在过去常常被用来建设距离（ distij）变量。自从这些文件 不包含共同的美国码头编码，使合并这些距离基准数据到贸易数据是存在问题的。作者为这些美国港口编码在两组数据库之间开

29、发了一个通讯为了合并这些数据基准。这相互联系着的数据库包含了数以万计的观察数据，其中一个观察数据是一个美国港口，国外港口和一个 six-digit HS 商品编码。如此大的一个数据库体现出了一些计算困难。为了减少这些困难，我们首先要通过进口量来限制我们的样品达到国外港口的前 100，由此覆盖了超过 81%的美国进口行为。第二，我们对我们每年的模型进行估量而不是所有的样品。每年的样品有成百上千个观察数据并且 每个在带有 8千兆字节的统计软件包的操作系统中花费 10小时以上的计算时间来使用数据管理统计绘图软件。 3、结果以及港口装卸效率的预算 在集中关注对于港口固定效应的评估（我们在港口效率上的措

30、施），一个简短的讨论提供了关于整体效能的模型。这个合适的模型基准相当大并且多年来保持稳定，通过 R2 统计排列变化从 0.9 到 0.92，这表明，我们的控制变量说明90%（或更多）的变异在进口费用。 F 数据确认统计意义对于我们每个固定效应都在 1%的现实性水平上。 4、对港口装卸效应措施的评估 （ 1）、美国港口有效措施 模型关于我们对表 格一的结果做出了评估，也包括了美国港口，国外港口和 6-digit 高温超导产品的固定效应。每个这些固定效应都是从 0 到 1%的显示性水平上的共同统计都是不同的。美国港口多年以来，我们的多有样品盒等级都从最少效能的港口提升到最佳效应。这些港口的固定效应

31、系数从进口方面给港口的影响上做出了评估，并且独立地从其他变量改变包括在我们的海退上。产品在我们的海退上有杂质固定效应，例如，那个港口的固定效应平均值应将从产品的差异性摆脱偏见，在混合型港口手柄的差异。低得（或者更负的）系数，降低美国港口关于进口费用中的费用以及所有其他 变量保持微笑，从而，成为更有效率的港口。 一个关于美国港口固定效应的测试和格尔夫波特预算揭示了许多关于墨西哥湾海岸，西海岸港口在登记更高的货物等级中超过 2 一个登记。这个火奴鲁鲁、夏威夷和圣胡安岛屿港口本质上离开条款效率在表格的底部，分别从0.349 到 0.609。 总的来说，有一个重大范围的预估的港口效率。只有在 0.05

32、 的奥克兰港口中 50 个港口中的其中 15 个，里面大致 5%的对奥克兰港的影响在进口费用上。平均每个港口有一个 0.08左右固定效益和围绕在标准差样本为 0.11数据上。 （ 2）、国外港口的有效措施 类似 于估计美国港口的固定效应，估计国外港口固定效应提供了外国港口的措施效率。相对于我们排除从我们外国港口荷兰的鹿特丹，有更小（或更负）系数，更有效率的港口。 5、总结 本研究通过简单统计使用工具统计从 1991 年到 2003 年美国港口的基准流量提供了新海洋的措施港口效率。不像以前落实的措施概观，它使用研究、 DEA和生产 /成本函数估计，本研究的方法论对于多个国家得到更广泛的样本并且多年来没有成本提供了这样一个评估。它在快速提供港口装卸效率商品与商品的基础上有很大的灵活性（比如，美国港口在处理钢铁产品上更有效率）。费用 比较高的并且有强烈基准的其他需求的方法论可能是像为什么美国海事管理局无法鉴定或提供任何港口装卸效率与最近国会的要求进行对照。超出重要角色的告知决策者，容易有效的港口装卸效率的措施可以使用附近的的未来研究者检查新问题的无数个方法，包括港口的演化效率随着时间的推移并且它影响着国际贸易的流动和国家的发展。