Pooling multivariate data under W, LR and LM tests

Two independent random samples are drawn from two multivariate normal populations with mean vectors μ1 and μ2 and a common variance-covariance matrix Σ. Ahmed and Saleh (1990) considered preliminary test maximum likelihood estimator (PMLTE) for estimating μ1 based on the Hotelling's T _N ², when it is suspected that μ1=μ2. In this paper, the PTMLE based on the Wald (W), Likelihood Ratio (LR) and Lagrangian Multiplier (LM) tests are considered. Using the quadratic risk function, the conditions of superiority of the proposed estimator for departure parameter are derived. A max-min rule for the size of the preliminary test of significance is presented. It is demonstrated that the PTMLE based on W test produces the highest minimum guaranteed efficiencies compared to UMLE among the three test procedures.     

股票市场对技术进步和经济增长的影响分析

运用跨时期固定替代弹性效用函数分析了股票市场的流动性对风险管理、先进技术选择和技术进步的影响,并运用格兰杰因果检验方法,考察中国股票市场与技术进步和经济增长的关系;认为中国股票市场的流动性是经济增长的真实原因,强调现阶段应注重提高中国股票市场的流动性,发挥股票市场在技术进步和经济增长中的作用。     

The Management of Risk: Application to the Welding Industry

The management of health risk in the welding industry is considered based on a discussion of the major sources of harm to welders arising from their employment (e.g., accidents and inhalation of fumes and gases). It is shown that present methods neither enable the assessment of the societal and human costs involved, nor permit the specific association of delayed health effects to occupational fume exposures. Reported accidents usually occur early in the working experience and contribute to a large number of working days lost, while fume exposures may contribute to a reduction in life quality which is poorly defined. It is concluded that risk management can only be attempted after much more information is made available concerning the origin, nature, and duration of health effects, especially as related to individual welding technologies and applications.     

Psychological mechanisms of investors in Chinese Stock Markets

The study investigated the psychological mechanisms of risky investment behaviors in Chinese Stock Markets. A 42-item questionnaire was developed and distributed to 1547 individual investors recruited by stratified random sampling from Nan Fang Bond Company. A speculative orientation and a low level of risk perception among Chinese investors were revealed. The results also showed that investors were deficient in investment knowledge and skills. Structural equation modeling was used to generate a risk perception-mediated model for investment behaviors. We found that information from organizational/institutional level can precipitate low risk perception and policy-oriented speculation of investors, which could be accounted for by the collectivistic culture in China and may not be beneficial to risk management in Chinese Stock Markets. Suggestions were made regarding the further development of stock markets in China.     

Using Automated Emergency Notification Systems to Inform the Public: A Field Experiment

Research and experience have shown that it can be difficult to get citizens to pay attention to risk messages and preparedness information in the absence of an actual emergency. As the use computerized systems that alert the public to hazards by automatically ringing their home phones increases, we thought it important to ask if tests of these "call down" systems can also be used to convey preemergency information. We worked with a local government to add instructions on how to shelter-in-place to the message on a routine test of a call down system. We then surveyed a test group and a control group before and after the test call and a second control group on after the call. The results indicate that the test call raised awareness of the emergency notification system without generating undue concern about the possibility of a chemical accident. Those who received the test call demonstrated significant improvements in their knowledge of how to shelter-in-place while no such improvement was observed in those who did not get the call. While the nature of the sample used in this study limits generalizability, we feel this outcome is positive enough to warrant further exploration of this method of disseminating risk information and preparedness instructions.     

Cognitive dissonance and risk denial: The case of cannabis use in adolescents

This paper integrates insights from both sociology and psychology into the economic approach of drug use. Within this theoretical framework, the utility provided by cannabis use depends on the ability to deny its riskiness, and this ability is a kind of human capital accumulated through earlier consumption. This assumption is tested with a dataset of French adolescents. A simultaneous equation model is estimated, with one equation for cannabis use, and one for risk denial. The results provide some empirical evidence in favour of the tested assumption, and they also cast doubt on the efficiency of preventive information at school.     

中美房贷险风险保障机制的比较研究

针对当前房贷险颓势引致运行不畅现象,应用比较分析方法,借鉴美国房贷险风险保障机制的先进经验,并结合我国的国情,找出并剖析影响房贷险正常运行的诸多因素,提出建立有效房贷险风险保障机制的解决方案与政策建议。     

Positioning terrorism in management and marketing: Research propositions

Terrorism poses both direct and indirect threats to the operations of the firm. It represents a market imperfection that increases transaction costs and creates barriers to the free flow of goods, affecting potential gains that would occur in the presence of unhindered exchange. Terrorism reflects the risk or actual encounter of violent acts, whose goal is to engender fear, coercion, or intimidation. We investigate terrorism and its association with marketing strategy and operations. Key concepts on terrorism are reviewed and a collection of propositions is offered. We highlight the pivotal roles of sourcing, production, distribution, pricing, communications, and general business strategy as functions influenced by, or capable of influencing, terrorism. Lastly, we offer managerial implications, as well as directions and guidelines for future research.     

The failure of meta-analytic asymptotics for the seemingly efficient estimator of the common risk difference

We consider the case of a multicenter trial in which the center specific sample sizes are potentially small. Under homogeneity, the conventional procedure is to pool information using a weighted estimator where the weights used are inverse estimated center-specific variances. Whereas this procedure is efficient for conventional asymptotics (e. g. center-specific sample sizes become large, number of center fixed), it is commonly believed that the efficiency of this estimator holds true also for meta-analytic asymptotics (e.g. center-specific sample size bounded, potentially small, and number of centers large). In this contribution we demonstrate that this estimator fails to be efficient. In fact, it shows a persistent bias with increasing number of centers showing that it isnot meta-consistent. In addition, we show that the Cochran and Mantel-Haenszel weighted estimators are meta-consistent and, in more generality, provide conditions on the weights such that the associated weighted estimator is meta-consistent.     

The Risks of Using Nuclear Energy Sources in Space: Some Lay Activists'Perceptions

A combination of directive and nondirective techniques was used to study the mental models of 30 lay activists regarding the risks of nuclear energy sources in space. Respondents'perceptions were compared with an "expert model" of the processes generating and controlling these risks, in terms of both the substance of their beliefs and several statistical measures of their performance. These analyses revealed a complex pattern of strengths and weaknesses. Their details are used to derive recommendations for formulating messages about these risks.