Forecasting portfolio-Value-at-Risk with nonparametric lower tail dependence estimates

We propose to forecast the Value-at-Risk of bivariate portfolios using copulas which are calibrated on the basis of nonparametric sample estimates of the coefficient of lower tail dependence. We compare our proposed method to a conventional copula-GARCH model where the parameter of a Clayton copula is estimated via Canonical Maximum-Likelihood. The superiority of our proposed model is exemplified by analyzing a data sample of nine different bivariate and one nine-dimensional financial portfolio. A comparison of the out-of-sample forecasting accuracy of both models confirms that our model yields economically significantly better Value-at-Risk forecasts than the competing parametric calibration strategy.     

Exchange rate contagion in Latin America

A regular vine copula approach is implemented for testing for contagion among the exchange rates of the six largest Latin American countries. Using daily data from June 2005 through April 2012, we find evidence of contagion among the Brazilian, Chilean, Colombian and Mexican exchange rates. However, there are interesting differences in contagion during periods of large exchange rate depreciation and appreciation. Our results have important implications for the response of Latin American countries to currency crises originated abroad.     

A number‐of‐modes reference rule for density estimation under multimodality

We consider kernel density estimation for univariate distributions. The question of interest is as follows: given that the data analyst has some background knowledge on the modality of the data (for instance, ‘data of this type are usually bimodal’), what is the adequate bandwidth to choose? We answer this question by extending Silverman's idea of ‘normal‐reference’ to that of ‘reference to a Gaussian mixture’. The concept is illustrated in the light of real data examples.     

基于时变Copula的我国股票市场联动性研究

通过运用Copula技术,构建4种Copula-GARCH模型,讨论金融市场的相关模式问题得出的结论是Joe-ClaytonCopula比正态Copula好,动态模型比静态模型要好。表明沪港股市确实存在非对称的相关变化规律。同时表明沪、港股票市场股市相关程度较小,两个市场联动性较弱,上海股市的波动具有相对的独立性,通过组合上海股市和香港股市的方式可以较好的降低投资风险。     

低温条件下泵站建设中大体积混凝土裂缝控制研究

文章结合西安市尚苑路雨水泵站工程中的大体积混凝土的设计与施工,对低温条件下进行施工的大体积混凝土的裂缝控制技术进行研究。     

基于Copula的股票型开放式基金的组合风险度量

本文在＂推出股指期货和融资融券＂的新政策下,结合t-EGARCH模型和Copula方法对股票型开放式基金进行分析.该模型能更好地捕捉资产间的非线性相关性,更符合现实市场.并在此基础上,利用蒙特卡洛模拟计算了景顺增长基金前十大重仓股票及其投资组合的VaR值,从而验证了模型的有效性。     

Portfolio optimization based on GARCH-EVT-Copula forecasting models

This study uses GARCH-EVT-copula and ARMA-GARCH-EVT-copula models to perform out-of-sample forecasts and simulate one-day-ahead returns for ten stock indexes. We construct optimal portfolios based on the global minimum variance (GMV), minimum conditional value-at-risk (Min-CVaR) and certainty equivalence tangency (CET) criteria, and model the dependence structure between stock market returns by employing elliptical (Student-$t$ and Gaussian) and Archimedean (Clayton, Frank and Gumbel) copulas. We analyze the performances of 288 risk modeling portfolio strategies using out-of-sample back-testing. Our main finding is that the CET portfolio, based on ARMA-GARCH-EVT-copula forecasts, outperforms the benchmark portfolio based on historical returns. The regression analyses show that GARCH-EVT forecasting models, which use Gaussian or Student-$t$ copulas, are best at reducing the portfolio risk.     

基于地下经济行为的博弈分析

第二次世界大战以后,经济学家在对传统经济进行反思的过程中,开始从地下经济角度来解释现实经济现象中宏观经济预测的偏离及菲力普斯曲线开始向上和向外盘旋现象。地下经济一般被认为是由那些企业或个人防止和逃避政府的管制、税收和监察的经济活动和由此获得的收入构成的。根据政府作为政策制定者和观察者及受调查者即企业或个人之间的关系,本文提供了一个相互作用系统的样板,通过政府和企业及个人之间在交税行为过程中产生的信号传递反馈系统,拟用一种不完全信息的动态博弈分析方法,论证得出信息系统的完整化、公开化、政府法律政策严明性及政府的相机抉择制度对社会经济发展的重要作用。     

降雨作用下土石混合体边坡力学参数弱化规律与稳定性分析

土石混合体边坡地质灾害是中国最为常见的地质灾害之一,而降雨是其主要诱发因素,降雨条件下边坡劣化机理研究是防灾减灾领域的重要研究方向.通过分析不同含水率条件下土石混合体力学性质试验数据,建立抗剪强度参数随含水率的演化方程;以此为基础,针对西南地区典型土石混合体边坡,考虑降雨条件下力学参数弱化的影响,采用Geostudio软件开展边坡稳定性分析.结果表明:演化方程能有效反映含水率增大对土石混合体抗剪强度具有显著的弱化效应;降雨强度的增大会显著降低边坡稳定性,降雨持时只是降雨过程中某一时刻值的体现,对边坡稳定性影响不大;降雨量与边坡安全系数呈明显线性负相关.研究成果可为土石混合体边坡地质灾害预测与防治提供技术支撑.     

Mixture representations for discrete Linnik laws

In this paper we give mixture representations for the discrete Mittag–Leffler and Linnik laws. Our results form the discrete analogues of the mixture representations for the generalized symmetric Linnik distribution obtained by P AKES (1998). As an application, we derive the infinite divisibility of mixtures of Mittag–Leffler distributions. Alternative mixture representations in terms of discrete stable distributions are also presented.