石油贸易、石油安全与我国的对策

石油对我国经济和国家安全至关重要。自从1993年我国成为石油净进口国以来,我国石油对外依存度逐年上升。自2003年后,国际石油价格爆涨,我国石油安全比以往任何时候都更危险。同时,我国石油贸易还存在越贵越买的问题。本文分析了我国石油安全形势,认为我国石油安全已经处于危险状态,在此基础上,进一步提出了提高我国石油安全和改善石油贸易的建议。     

自然资源依赖对城乡收入差距的影响研究

［目的］针对全国31个省（市、区）（不含港澳台地区）、自然资源依赖度高的地区和自然资源依赖度低的地区,从整体和分区域研究自然资源依赖对城乡收入差距的影响,探究不同区域其影响程度的差异性,进而为弱化各区域城乡收入差距,解决由城乡收入差距拉大造成的各类社会矛盾具有重要的现实意义。［方法］从理论上分析了自然资源依赖对城乡收入差距的影响,并利用1999—2017年的省级面板数据,运用固定效应模型,从全国和分区域实证分析了自然资源依赖对城乡收入差距的影响。［结果］针对全国,自然资源依赖会拉大城乡收入差距; 分区域结果,针对自然资源依赖度高的地区,自然资源依赖拉大城乡收入差距; 针对自然资源依赖度低的地区,自然资源依赖对城乡收入差距影响不显著。［结论］为缩小城乡收入差距,需要降低经济体对自然资源的依赖,针对自然资源依赖度高的地区,政府通过将部分自然资源收益转化为农业创新基金和农村基础设施投入,促进自然资源收益向农村公共资本转化,完善现有的自然资源收益分配及转化制度; 鼓励资源型产业技术创新,加大研发投入,延长资源产业链; 加大农村教育投入、提升农村人力资本质量。     

多维邻近性对校企创新合作绩效的影响研究

在百年未有之大变局的时代背景下,加强校企创新合作、促进科技成果转化是提升国家创新实力、促进国家科技变革的关键。然而,总体上看中国校企创新合作绩效不容乐观,如何提升其整体绩效也就成了亟需解决的问题。多维邻近性作为衡量校企创新合作绩效的常用前置因素,其影响关系也在不断随外界环境的变化而变化。因而文章在理论分析及案例调研的基础上,构建了多维邻近性的内涵维度以及对校企创新合作绩效的影响关系模型,并通过问卷调查等方法结合结构方程对概念模型进行探索验证。结果表明：认知、技术及关系邻近性通过合作信任度和合作依赖度两个中介正向影响校企创新合作绩效,地理邻近性的作用在下降,政府引导支持和技术中介服务在两者之间起的调节作用互补且显著。     

Inference with Dependent Data in Accounting and Finance Applications

We review developments in conducting inference for model parameters in the presence of intertemporal and cross‐sectional dependence with an emphasis on panel data applications. We review the use of heteroskedasticity and autocorrelation consistent (HAC) standard error estimators, which include the standard clustered and multiway clustered estimators, and discuss alternative sample‐splitting inference procedures, such as the Fama–Macbeth procedure, within this context. We outline pros and cons of the different procedures. We then illustrate the properties of the discussed procedures within a simulation experiment designed to mimic the type of firm‐level panel data that might be encountered in accounting and finance applications. Our conclusion, based on theoretical properties and simulation performance, is that sample‐splitting procedures with suitably chosen splits are the most likely to deliver robust inferential statements with approximately correct coverage properties in the types of large, heterogeneous panels many researchers are likely to face.     

Internal and external factors in innovation persistence

This paper contributes to the analysis of the persistence of innovation activities, as measured by total factor productivity (TFP), and explores its internal and external determinants stressing its path-dependent characteristics. The external conditions, namely the quality of local knowledge pools and the strength of the Schumpeterian rivalry, along with the internal conditions (the actual levels of dynamic capabilities, as proxied by wage levels and firm size) exert a specific and localised effect upon the persistent introduction of innovations. A multiple transition probability matrixes (MTPMs) approach has been implemented to capture the contingent effects of external factors on long-term innovation persistence. The empirical analysis of the dynamics of firm-level TFP for a sample of approximately 7000 Italian manufacturing companies observed during the years 1996–2005 is based on both the comparison of different transition probability matrixes and on dynamic discrete choice panel data models. The evidence provided by the test of MTPMs in sub-periods suggests that innovation persistence is path-dependent, as opposed to past-dependent.     

Purchasing Power Parity and the European single currency: Some new evidence

The effect of the single currency on the Purchasing Power Parity (PPP) hypothesis is examined in this study for the 15 EU countries, vis a vis the US dollar, before and after the advent of the euro. Standard as well as nonlinear unit root tests are employed on the time series dimension. Unit root tests reject PPP and the highest half-lives are observed after the introduction of the single currency. Panel unit root (Pesaran, 2007) and stationarity tests (Hadri and Kurozumi, 2008) that take into account cross-sectional dependence are also estimated. The results remain inconclusive as panel stationarity tests fail to support PPP whereas panel unit root tests fail to reject PPP for the whole sample and for the period before the introduction of the single currency.     

Global financial crisis and dependence risk analysis of sector portfolios: a vine copula approach

We use regular vine (r-vine), canonical vine (c-vine) and drawable vine (d-vine) copulas to examine the dependence risk characteristics of three 20-stock portfolios from the retail, manufacturing and gold-mining equity sectors of the Australian market in periods before, during and after the 2008–2009 global financial crisis (GFC). Our results indicate that the retail portfolio is less risky than the manufacturing counterpart in the crisis period, while the gold-mining portfolio is less risky than both the retail and manufacturing sector portfolios. Both the retail and gold stocks display a higher propensity to yield positively skewed returns in the crisis periods, contrary to the manufacturing stocks. The r-vine is found to best capture the multivariate dependence structure of the stocks in the retail and gold-mining portfolios, while the d-vine does it for the manufacturing stock portfolio. These findings could be used to develop dependence risk- and investment risk-adjusted strategies for investment, rebalancing and hedging which more adequately account for the downside risk in various market conditions.