Estimating gravity equation models in the presence of sample selection and heteroscedasticity

Gravity models are widely used to explain patterns of trade. However, two stylized features of trade data, sample selection and heteroscedasticity challenge the estimation of gravity models. We propose a two-step method of moments (TS-MM) estimator that deals with both issues. The Monte-Carlo experiments show that the TS-MM estimates are resistant to various combinations of sample selection and heteroscedasticity. Moreover, the TS-MM estimator performs reasonably well even when the data generating process deviates from the TS-MM assumptions. We revisit the world trade in 1990 to illustrate the usefulness of the proposed model, with emphasis on the identification of the extensive margin of trade.     

Overcoming environmental scarcity,inequality and structural imbalance in the world economy

The world economy faces two major threats: increasing environmental degradation and a growing gap between rich and poor. The root cause is that natural resources—or natural capital—is underpriced, and hence overly exploited, whereas human capital—the skills embodied in the workforce—is insufficient to meet demand. This outcome has three important consequences. First, all sectors of an economy will use too much natural resources relative to skilled labor. Second, the skilled workers throughout the economy will have higher real incomes and thus will be better off. Third, wealth inequality will increase, as the income gap between skilled and unskilled workers widens. Addressing this structural imbalance requires correcting the two underlying distortions, which are the chronic under-pricing of natural capital and the under-investment in human capital. This must be accompanied by a new suite of policies to provide improved incentives for more balanced wealth creation.     

Expenditure elasticities of the demand for leisure services

Although some research has already focused on the analysis of expenditure elasticities of leisure demand, some shortcomings with regard to the content and the underlying theoretical model as well as the applied methods exist. This article aims at avoiding these problems to provide consistent derivatives of leisure service expenditure elasticities. Therefore, a regular demand system is derived from microeconomic duality theory. To implement leisure specific demand factors (i.e. demand- and supply-based sports and recreational opportunities as well as sports and recreational preferences) while still being consistent with neoclassical demand theory, the basic model is extended by applying the demographic translation framework. Data of the continuous household budget survey (n?=?7724) from Germany is used for the estimation of the derived demand system. It is shown how sensitive the results are depending on the applied (censored) regression model: 16 out of 18 analysed services are indicated as luxury goods based on the findings of the Tobit model type I but as necessities based on the findings of the Tobit model type II. Possible implications are presented and discussed.     

西部地区县域经济“要素失衡与缺失陷阱”的破解路径

"要素失衡与缺失陷阱"是我国西部地区县域经济现状的真实写照。自然资源外流、产业结构失衡、资金外流、人才缺失、技术缺失、信息滞后、政府制度供给匮乏都是"要素失衡与缺失陷阱"的典型表现。因此,修缮和填补这些"陷阱"已成为发展西部地区县域经济的当务之急。而找到正确的方法,才能让"陷阱"填平,不再出现坍塌的危险。大力推进西部地区县域体制机制改革;大力推进"三化"联动发展;构建完备的县域经济发展软硬件体系;树开放胸怀,提高决策者、执行者、普通大众的意识水平,则是西部地区县域经济"要素失衡与缺失陷阱"破解路径。     

Consumer Valuation of Alternative Meat Origin Labels

Results from a split‐sample survey of the US population reveal consumers prefer meat products carrying origin information to unlabelled alternatives. Consumers are largely unaware of origin labelling laws and are indifferent to an important aspect of the implementation of current mandatory country of origin information rules in the US. In particular, consumers value meat products labelled ‘Product of North America’ approximately the same as ‘Product of United States’. Despite the similarity of these two labels, they have vastly different implications in terms of trade and segregation costs. Our results suggest that a transition from one label to the other is equally satisfying for the consumer while being less costly for processors and more acceptable to trade partners.     

我国经济内部失衡与外部失衡关系的实证分析——基于存贷差和外汇储备变动量的关系

我国经济主要面临内部失衡和外部失衡的矛盾,即存贷差过大和外汇储备过多的矛盾。本文经过理论模型的推导,证明了存贷差和外汇储备之间存在一定的关系．并通过实证分析对这一关系进行检验,发现存贷差是外汇储备的格兰杰原因。     

China as a Global Manufacturing Powerhouse： Strategic Considerations and Structural Adjustment

This study examines the nature and consequences of China＇s rise to the center of world economic affairs through manufacturing-led development. Our historical analysis shows that China is still well short of the point in its developmental process where its growth might be reasonably expected to slow, or the energy, resource and carbon intensity of growth to recede. The study argues that the current trajectory of industrialization will have to be altered when China becomes more actively engaged in dealing with structural issues at home and abroad against the background of the unwinding of global imbalances. One profitable strategy that China might employ wouM be to approximate the incredibly fruitful mass-market integration efforts of the USA that eventually elevated it to its position of global primacy. The cyclical re-emergence of excess capacity in Chinese heavy industry, serious questions about the medium term ability of other major regions to accommodate further large gains in Chinese market share, and the stark conflict between the contemporary style of industrial development and the health of the biosphere indicate strongly that now is the time to catalyze the required adjustment and reform processes that will underpin sustainable long-run prosperity.     

支持向量机在航材供应模型中的研究

针对部队航材供应量预测过程中,样本采集数目较少的实际情况,采用了一种新的预测方法—支持向量机。该方法基于统计学习理论的原理,较好地解决了小样本的学习问题。并以某部队2000～2007年某项航材供应量为学习样本,建立了该项航材的供应量预测模型。计算结果表明,这种方法比传统的方法具有更少的误差和更好的预测精度。     

小样本训练集下人脸图像超分辨率重构算法

文章提出了一种针对小样本训练集的人脸图像超分辨率重构算法。该算法在马尔可夫网络模型的基础上,将视觉相容性检查准则引入到候选分块的匹配准则中,提高了匹配精度和块间兼容性。将权值机制融合进图像的重构过程,强化了训练集的有用性。实验表明,在小样本训练集下,算法能有效地抑制块效应和局部失真现象,明显改善超分辨率图像的质量。     

中美贸易结构性失衡:基于赫克歇尔—俄林模型的分析

把中美贸易失衡问题置于国际分工的新格局下进行分析,不难发现,中美贸易逆差的根本原因在于世界头号服务业强国与世界头号制造业大国之间在服务贸易和商品贸易上发生的结构性失衡。中美贸易失衡与全球服务贸易和商品贸易在自由化进程上的非对称性紧密联系在一起。考虑到全球服务贸易自由化的缓慢进展,以及中国对服务贸易自由化已经做出的承诺水平,中美贸易的结构性失衡在相当长的时期内将难以消除。