A Hausman-type test to detect the presence of influential outliers in regression analysis

In regression analysis, classical estimations may be excessively influenced by a few atypical observations. We propose a Hausman-type test to balance robustness and efficiency and to check whether a robust method should be implemented. An economic application is presented.     

Maxbias curves of robust scale estimators based on subranges

A maxbias curve is a powerful tool to describe the robustness of an estimator. It is an asymptotic concept which tells how much an estimator can change due to a given fraction of contamination. In this paper, maxbias curves are computed for some univariate scale estimators based on subranges: trimmed standard deviations, interquantile ranges and the univariate Minimum Volume Ellipsoid (MVE) and Minimum Covariance Determinant (MCD) scale estimators. These estimators are intuitively appealing and easy to calculate. Since the bias behavior of scale estimators may differ depending on the type of contamination (outliers or inliers), expressions for both explosion and implosion maxbias curves are given. On the basis of robustness and efficiency arguments, the MCD scale estimator with 25% breakdown point can be recommended for practical use. Received: February 2000     

汇率与股价变动关系:基于汇改后数据的实证研究

研究我国2005年7月汇率制度改革后汇率与股市的关系及其传导机制,有助于深刻认识金融市场联动特征,对于防范金融市场风险和完善我国资本市场、外汇市场等的改革具有重要的理论和实践意义。本文实证发现了汇率和股价存在着长期均衡的协整关系;从长期来看,两者关系符合流量导向模型,上证指数受到汇率长期影响,从短期来看,股市和汇市存在着交互影响,汇率变化影响股指变动有时滞。运用滚动窗口的Granger检验和加入其他重要宏观变量的多变量协整检验,本文证明了这种长期关系具有较强的稳健性。进一步从板块指数与汇率的关系来看,房地产、金融、民航、石化、钢铁指数均与汇率存在着长期的协整关系,汇率变化是这些板块指数的Granger原因。最后,本文对实证结果做出分析并指出了相应的政策含义。     

Bounds for Ratios of Posterior Expectations: Applications in the Collective Risk Model

This paper considers the collective risk model for the insurance claims process. We will adopt a Bayesian point of view, where uncertainty concerning the specification of the prior distribution is a common question. The robust Bayesian approach uses a class of prior distributions which model uncertainty about the prior, instead of a single distribution. Relatively little research has dealt with robustness with respect to ratios of posterior expectations as occurs with the Esscher and Variance premium principles. Appropriate techniques are developed in this paper to solve this problem using the k -contamination class in the collective risk model.     

Dissecting the idiosyncratic volatility anomaly

The idiosyncratic volatility (IVOL) anomaly, documented in Ang, et al. (2006), has garnered a great deal of attention in the literature. Yet questions remain regarding the robustness and pervasiveness of the IVOL anomaly, with a particular concern that the IVOL anomaly might simply be the manifestation of market microstructure effect. In this paper, we show that the IVOL anomaly is strong and pervasive after we exclude stocks most susceptible to market microstructure noise — such as microcap stocks, penny stocks, and stocks with strong short-term return reversal. These results are robust to equal-weighting or value-weighting stocks in the IVOL portfolios. Our findings suggest that rather than being the cause of the anomaly, market microstructure noise actually weakens the IVOL anomaly.     

数字水印对Stirmark攻击的鲁棒性分析

随着计算机、网络和通信技术的飞速发展，特别是Internet的普及，信息的安全保护问题日益突出。数字水印技术作为知识产权保护的有效手段，易受到各种恶意攻击而导致水印无法提取。本文研究了数字水印在各种常见攻击下的鲁棒性度量问题，以标准测试工具Stirmark软件为平台，定量分析了Digimarc水印对信号处理变换和几何变换攻击的鲁棒性，所得结果有助于数字水印算法的设计和改进，使其具有更好的安全性和稳健型。     

Chi-Square Tests Under Models Close to the Normal Distribution

Many test statistics follow a χ² distribution because a normal model is assumed as underlying distribution. In this paper we obtain good analytic approximations for the p-value and the critical value of χ² tests when the underlying distribution is close but different from the normal model. With these approximations we study the robustness of validity of χ² tests     

Retail supply chain network design under operational and disruption risks

Designing robust and resilient retail networks under operational and disruption risks can create substantial competitive advantage. In this paper, a deterministic multiple set-covering model is first proposed. Then, it is extended to a possibilistic scenario-based robust model by scenario generation and disruption profiling to design a robust and resilient retail network. The developed models are validated through randomly generated examples and a real case study in retailing. Numerical results demonstrate that designing retail chains without considering operational and disruption risks is really misleading. Also, multiple covering of retail stores as the measure of redundancy increases the network’s resilience significantly.     

Garbling of signals and outcome equivalence

In a game with incomplete information players receive stochastic signals about the state of nature. The distribution of the signals given the state of nature is determined by the information structure. Different information structures may induce different equilibria.Two information structures are equivalent from the perspective of a modeler, if they induce the same equilibrium outcomes. We characterize the situations in which two information structures are equivalent in terms of natural transformations, called garblings, from one structure to another. We study the notion of ‘being equivalent to’ in relation with three equilibrium concepts: Nash equilibrium, agent normal-form correlated equilibrium and the belief invariant Bayesian solution.