A Bayesian approach for more reliable tail risk forecasts

This paper demonstrates that existing quantile regression models used for jointly forecasting Value-at-Risk (VaR) and expected shortfall (ES) are sensitive to initial conditions. Given the importance of these measures in financial systems, this sensitivity is a critical issue. A new Bayesian quantile regression approach is proposed for estimating joint VaR and ES models. By treating the initial values as unknown parameters, sensitivity issues can be dealt with. Furthermore, new additive-type models are developed for the ES component that are more robust to initial conditions. A novel approach using the open-faced sandwich (OFS) method is proposed which improves uncertainty quantification in risk forecasts. Simulation and empirical results highlight the improvements in risk forecasts ensuing from the proposed methods.     

Effect of credible quality investment with Bertrand and Cournot competition

We show how credible revelation and ability to commit to quality choice effect equilibrium qualities and welfare when product market is either Bertrand or Cournot competition. We show that results depend on the type of competition but not generally on the cost of quality function. We show that with Bertrand competition, the equilibrium qualities are lower with credible commitment. Competition is moderated and producer surplus is higher and consumer surplus lower. With Cournot competition, higher quality will be better but lower quality will be worse with credible commitment. Consumer surplus is always greater with credible commitment and if cost does not increase too quickly with quality, producer surplus will also increase. Thus credible commitment is a collusive device with Bertrand competition but it can improve social welfare with Cournot competition. Received: February 8, 2000; revised version: February 14, 2002 RID="*" ID="*" The idea of this paper originated in the weekly workshops of Mordecai Kurz at Stanford. I am forever in debted to Mordecai and fellow students – Luis Cabral, Peter DeMarzo, John Hillas, Michihiro Kandori, Steve Langois, Patrick McAllister, Steve Sharpe, Peter Streufert, Steve Turnbull and Gyu-Ho Wang – for their criticism and encouragement. I also benefited from comments from Yi-Heng Chen, Jin-Li Hu, Kala Krishna, Jinji Naoto, Thomas J. Prusa, and Shyh-Fang Ueng at various later stages of this work. Last but not least, I am grateful for the detailed comments of the referee.     

国际证券市场联动程度的实证分析

20世纪80年代以来,通过国际证券投资分散风险已经形成一种可行手段,然而,随着全球经济一体化趋势的强化,国际证券市场也正在经历着一体化趋势,证券市场联动关系越来越明显,这必然会使国际投资多样化空间变小,进而会侵蚀掉国际多样化投资收益.有鉴于此,本文使用协相关参数分析、平稳性检验、多元协整检验、协整向量参数零配载限制检验、基于VECM的Granger因果性检验等计量技术测度国际证券市场联动程度,为国际证券投资提供量化参考.     

工具变量法综列单位根检验的有偏性及其修正

Chang（2002）基于非线性工具变量估计，提出了对截面相关综列数据进行单位根检验的SN检验，在综列数据生成过程不舍飘移和时间趋势时具有良好的表现。但我们的研究表明，在非平稳综列数据含有确定性趋势时，SN检验是有偏的，不再服从标准正态的渐近分布，而需要进行修正。本文基于蒙特卡罗仿真试验提出了一种简便的修正方法，修正后的SN检验统计量渐近分布为标准正态分布。仿真结果表明，修正后的SN检验具有更好的有限样本性质和较高的检验势。     

欧盟REACH法令对中国化工产品出口的影响分析

欧盟REACH法令的实施将促进我国化学工业的发展,但在短期内会导致我国出口欧盟化工产品和进口化工产品成本上升,降低出口产品竞争力,部分产品甚至退出欧盟市场,其他国家可能纷纷效仿欧盟,引起连锁反应。应对该种技术性壁垒,我国政府和行业协会应加大宣传REACH法令的力度,加快国内相关立法,推进国内实验室的GLP认证工作。另外,化学品生产企业应提高自身产品质量,做好化学品注册的可行性分析和预注册工作。     

How many voters are needed for paradoxes?

Summary. This paper presents a general procedure for finding profiles with the minimum number of voters required for many important paradoxes. Borda's and Condorcet's classic examples are revisited as well as generalizations. Using Saari's procedure line, we obtain an upper bound for the minimum number of voters needed for a profile for which the Condorcet winner is not strictly top ranked for all weighted positional procedures. Also we give a simple upper bound on the minimum number of voters needed for a set of prescribed voting outcomes. In contrast to situations wherein small numbers of voters are needed, we consider paradoxes requiring arbitrarily large numbers of voters as well as large numbers of alternatives. Finally we indicate connections with statistical rank based tests. Received: April 18, 2001; revised version: May 25, 2001     

Trees and decisions

Summary. The traditional model of sequential decision making, for instance, in extensive form games, is a tree. Most texts define a tree as a connected directed graph without loops and a distinguished node, called the root. But an abstract graph is not a domain for decision theory. Decision theory perceives of acts as functions from states to consequences. Sequential decisions, accordingly, get conceptualized by mappings from sets of states to sets of consequences. Thus, the question arises whether a natural definition of a tree can be given, where nodes are sets of states. We show that, indeed, trees can be defined as specific collections of sets. Without loss of generality the elements of these sets can be interpreted as representing plays. Therefore, the elements can serve as states and consequences at the same time.Received: 23 January 2003, Revised: 2 November 2003, JEL Classification Numbers: C72, D70. Correspondence to: Klaus RitzbergerWe are grateful to Larry Blume, Ariel Rubinstein, Jörgen Weibull, an anonymous referee, and seminar participants at the universities of Vienna, Salamanca, and Heidelberg for helpful comments. Financial support from the Austrian Science Fund (FWF) under project P15281 is also gratefully acknowledged.     

我国公共投资规模效率实证分析

我国公共投资规模连年扩大,改善了生活环境和生产条件,但是否存在投资过度的风险?本文运用生产函数模型分析了公共投资规模效率存在的条件,使用协整的方法分析了大口径和小口径公共投资规模的最优规模,得出我国公共投资规模不足的结论。     

湘北环湖红壤丘岗区生态经济特征及发展途径初探——以盘塘红壤实验区为例

本文通过对盘塘红壤开发实验基地区域生态经济特征及存在问题的分析,初步提出了该区生态经济深度发展的主要途径,并就整个湘北环湖红壤丘岗区生态经济发展提出了几点粗浅看法。     

中国饲料工业期货的价格发现实证研究

本文借助向量自回归模型、协整检验、误差修正模型、方差分解、脉冲响应函数等方法,以中国唯一的饲料工业期货———大连商品交易所豆粕期货品种为例,研究了期货价格与现货价格之间的动态关系,定量刻画了期货市场在价格发现中的作用。研究结果显示:豆粕期货价格与现货价格存在相互引导关系,并且期货与现货价格之间存在长期均衡关系,对豆粕期货来说,期货市场在价格发现功能中起到主导作用。