交通投资对中国经济增长的影响

许多发展经济学家论证了基础设施建设对发展中国家经济增长的重要性。本文收集中国28个省份1985—2006年的面板数据验证交通投资对我国经济增长的影响。基于系统广义矩估计（GMM）方法,本文得到的结论是交通运输投资对经济增长有着显著的正向影响,其短期和长期的产出弹性分别为0．023和0．062。这也就是说交通运输投资每增加1个百分点,从短期来看将会导致经济增长0．023个百分点,从长期来看将会导致经济增长0．062个百分点。     

Exact and asymptotic tests for possibly non-regular hypotheses on stochastic volatility models

We study the problem of testing hypotheses on the parameters of one- and two-factor stochastic volatility models (SV), allowing for the possible presence of non-regularities such as singular moment conditions and unidentified parameters, which can lead to non-standard asymptotic distributions. We focus on the development of simulation-based exact procedures–whose level can be controlled in finite samples–as well as on large-sample procedures which remain valid under non-regular conditions. We consider Wald-type, score-type and likelihood-ratio-type tests based on a simple moment estimator, which can be easily simulated. We also propose a C(α)-type test which is very easy to implement and exhibits relatively good size and power properties. Besides usual linear restrictions on the SV model coefficients, the problems studied include testing homoskedasticity against a SV alternative (which involves singular moment conditions under the null hypothesis) and testing the null hypothesis of one factor driving the dynamics of the volatility process against two factors (which raises identification difficulties). Three ways of implementing the tests based on alternative statistics are compared: asymptotic critical values (when available), a local Monte Carlo (or parametric bootstrap) test procedure, and a maximized Monte Carlo (MMC) procedure. The size and power properties of the proposed tests are examined in a simulation experiment. The results indicate that the C(α)-based tests (built upon the simple moment estimator available in closed form) have good size and power properties for regular hypotheses, while Monte Carlo tests are much more reliable than those based on asymptotic critical values. Further, in cases where the parametric bootstrap appears to fail (for example, in the presence of identification problems), the MMC procedure easily controls the level of the tests. Moreover, MMC-based tests exhibit relatively good power performance despite the conservative feature of the procedure. Finally, we present an application to a time series of returns on the Standard and Poor’s Composite Price Index.     

Value Functions for Prospect Theory Investors: An Empirical Evaluation for U.S. Style Portfolios

The main aim of this article is to provide a general behavioral analysis that proposes a series of different value functions for prospect theory (PT) investors incorporated into behavioral reward-risk models that are finally solved so as to provide some specific optimal solutions. To do this, general behavioral reward-risk models, which contain all the basic elements of the PT, are first set up. Two reward and risk measures, the upper partial moment and the lower partial moment, are subsequently used to create the various value functions. The technical difficulties arising during the behavioral maximization process are overpassed by adapting the Rubinstein [1982 Rubinstein, R. Y. “Generating Random Vectors Uniformly Distributed Inside and On the Surface of Different Regions.” European Journal of Operational Research, 10, (1982), pp. 205–209.[Crossref], [Web of Science ®] , [Google Scholar]] algorithm. The results show that agents differentiate their behavior according to their type of preferences (S-shaped, reverse S-shaped, kinked convex, and kinked concave value function) but they seem to always prefer small capitalization and high positively skewed value stock portfolios. Probability distortion also affects the optimal solutions of the problem, independently of the employing weighting functional form; when subjective probabilities are employed the optimal weights of the most risky positively skewed assets seem to increase. Probability distortion has an additional important effect on optimal perspective values of the problem driving to a significant increase.     

中国股票市场外国投资者所有权投资的限制与市场分割

本文针对中国股票市场1992-1997年度的A股和B股的市场分割问题进行研究,并讨论了B股大幅度折价的原因.研究发现A、B股价差的主要原因是B股市场缺乏流动性.B股相对缺乏流动性导致了投资者较高的期望收益,因此定价较低,以补偿投资者增加的交易成本.但是,在这两类股票中,B股价格比A股价格更接近于市场基本面.因此,本文认为,1992-1997年度的中国股票市场,实际上是A股溢价,而不是B股折价.     

Gamma-minimax estimation of a multivariate normal mean

Summary The mean vector of a multivariate normal distribution is to be estimated. A class Γ of priors is considered which consists of all priors whose vector of first moments and matrix of second moments satisfy some given restrictions. The Γ-minimax estimator under arbitrary squared error loss is characterized. The characterization follows from an application of a result of Browder and Karamardian published in Ichiishi (1983) which is a special version of a minimax inequality due to Ky Fan (1972). In particular, it is shown that within the set of all estimators a linear estimator is Γ-minimax. The authors would like to thank the Deutsche Forschungsgemeinschaft for financial support.     

在一集中弯矩作用下悬臂矩形板的弯曲

在本文中,应用功的互等定理进一步研究了在一集中弯矩作用下悬臂矩形板的弯曲问题。该法简单、通用。     

Equilibrium moment restrictions on asset returns: normal and crisis periods

Empirically, the covariance between stock returns varies with their volatility. We seek a robust theoretical explanation of this. With minimal assumptions, we model stochastic properties of equilibrium returns which result from the interaction between inter-temporal traders and noisy, price-sensitive short-term traders. The inter-temporal traders can have arbitrary investment rules, preferences and information. In all cases we find a set of restrictions between second moments of equilibrium returns. With two assets there is also a bound on the correlation between asset returns. Estimation with second moments of global stock returns supports our theoretical framework. Higher volatility in at least one market can increase comovement among markets. With globalization, covariances between two stock markets can also affect covariances between two other stock markets. We also find that the changes in trader behavior between normal and crisis periods lead to changes in the moment restrictions between asset returns.     

Fear itself: How risk sensitive firms can give demand shocks bite

Many economists believe that recessions arise when aggregate demand is insufficient to support full employment. However, replicating this intuition within a real business cycle (RBC) model has proven surprisingly challenging. Rather than eliciting a contraction, lower consumer demand leads to greater household savings in many such models, fueling new investment and causing the economy to expand. The present paper proposes a novel way to resolve this apparent paradox: risk-averse firms. In the model to follow, cautious firms reduce their demand for investment prior to a recession. This contraction in the demand for capital overcomes the increased supply arising from consumer savings and restores intuitive business cycle behavior. In particular, the paper demonstrates that the model economy contracts when subjected to an uncertainty shock in consumer demand, mimicking a pre-recessionary environment in which firms, fearing a lack of orders, precipitate the downturn by reducing capital expenditures. These results are consistent with microeconomic evidence that uncertainty, particularly uncertainty about future demand, is the primary reason for firms shedding workers or scaling down operations in advance of an economic downturn. More generally, they imply that firm's attitudes towards risk shouldn't be ignored in modern macroeconomic models.     

A term structure model for dividends and interest rates

Over the last decade, dividends have become a standalone asset class instead of a mere side product of an equity investment. We introduce a framework based on polynomial jump‐diffusions to jointly price the term structures of dividends and interest rates. Prices for dividend futures, bonds, and the dividend paying stock are given in closed form. We present an efficient moment based approximation method for option pricing. In a calibration exercise we show that a parsimonious model specification has a good fit with Euribor interest rate swaps and swaptions, Euro Stoxx 50 Index dividend futures and dividend options, and Euro Stoxx 50 Index options.     

多肋钢桁架拱桥合拢技术的探讨

通过对多肋钢桁架拱桥不同合拢方式的分析比较,得出了在不同温度的影响下,采取不同的合拢方式成拱后的位移、内力以及弯矩是不同的,因此,合理的合拢方案有助于提高桥梁的线形,改善主拱肋的受力。