Multivariate Cox Hidden Markov models with an application to operational risk

ABSTRACT

Modeling multivariate time-series aggregate losses is an important actuarial topic that is very challenging due to the fact that losses can be serially dependent with heterogeneous dependence structures across loss types and business lines. In this paper, we investigate a flexible class of multivariate Cox Hidden Markov Models for the joint arrival process of loss events. Some of the nice properties possessed by this class of models, such as closed-form expressions, thinning properties and model versatility are discussed in details. We provide the expectation-maximization (EM) algorithm for efficient model calibration. Applying the proposed model to an operational risk dataset, we demonstrate that the model offers sufficient flexibility to capture most characteristics of the observed loss frequencies. By modeling the log-transformed loss severities through mixture of Erlang distributions, we can model the aggregate losses. Finally, out-of-sample testing shows that the proposed model is adequate to predict short-term future operational risk losses.     

翻译法与交际法互补研究

翻译法和交际法是外语教学两种常用的方法.外语教学界关于这两种教学法的争论由来已久,比较翻译法和交际法有其各自的优点和缺点,教师在大学英语教学实践中应正确对待两种教学方法,努力做到各取其长,融合贯通,相互补充.     

An essay on conceptualization of issues in empirical accounting research

Empirical research in accounting has lately focused much on sophisticated statistical methodology and econometrics and relatively less on conceptualization of the issues concerned. This essay is written to highlight the conceptualization of the issues as an important ingredient of empirical research in accounting. I present two methods of conceptualization – the single-entity approach and the game theoretic approach. I give several examples in accounting research to explain the conceptualization process. I hope that this essay will fill a much needed void in the research process in accounting and restore the balance between conceptualization and methodology.     

理工类大学生科学方法教育探析

文章对科学方法和科学方法教育的概念进行了界定,阐述了对大学生开展科学方法教育的重要意义,并着重对大学生科学方法教育的途径进行了探讨。这对理工类大学生科学方法教育有着现实意义。     

A note on a semiparametric approach to estimating financing constraints in firms

In this paper, we present a novel approach to modeling financing constraints of firms. Specifically, we adopt an approach in which firm-level investment is a nonparametric function of some relevant firm characteristics, cash flow in particular. This enables us to generate firm-year specific measures of cash flow sensitivity of investment. We are therefore able to draw conclusions about financing constraints of individual firms as well as cohorts of firms without having to split our sample on an ad hoc basis. This is a significant improvement over the stylized approach that is based on comparison of point estimates of cash flow sensitivity of investment of the average firm of ad hoc sub-samples of firms. We use firm-level data from India to highlight the advantages of our approach. Our results suggest that the estimates generated by this approach are meaningful from an economic point of view and are consistent with the literature.     

Indian textile suppliers' sustainability evaluation using the grey approach

Textile supply chains consist of multinational garment retailers (customers), garment manufacturers (suppliers), and ancillary suppliers (suppliers to manufacturers). This paper evaluates suppliers' within the Indian textile and clothing industry (both garment manufacturers and ancillary suppliers) using sustainability criteria. Examining a sample of sixty-three suppliers and six sustainability criteria (i.e. discrimination, abuse of human right, child labor, long working hours, unfair competition, and pollution), we categorize suppliers into the three categories of ‘good performer’, moderate performer’, and ‘performance not up to expectation’. Since all the criteria are potentially subjective, we have employed the grey approach for analysis. The results indicate that the criterion of long working hours is a critical one for both categories of suppliers; in the case of garment manufacturers, we found that pollution and unfair competition were the most important criteria. In addition, employing child labor was found to be a critical criterion in the case of ancillary suppliers.     

Status of development,regulation and adoption of GM agriculture in Africa: Views and positions of stakeholder groups

The use of genetically modified (GM) crop technology in tackling food security problems and poverty reduction in Africa continues to generate debates over its benefits and safety. Only four countries, South Africa, Sudan, Burkina Faso and Egypt have commercialized GM crops in Africa but controversy surrounds current cultivation of GM maize in Egypt. Our study provides new perspectives on the status, development and regulation of GM crops through examining the views of 305 stakeholders in six African countries across four regions: South Africa, Kenya (East Africa), Egypt and Tunisia (North Africa), Ghana and Nigeria (West Africa), supplemented by interviews with relevant international organizations. The study revealed the challenges leading to the development of biosafety regulatory frameworks and the role of individual stakeholders in the facilitation of GM crops across African countries. This study also revealed that some countries may go through a Fiber–Feed–Food (F3) approach to adopt GM crops where Bt cotton will be adopted first followed by GM crops for livestock feed while undergoing all the necessary assessments before producing GM foods for human consumption. An overwhelming majority of stakeholders placed emphasis on risk analysis (risk assessment and management) in view of limited capacity, lack of scientific expertise and public concern, and encouraged a centralized approach to risk assessment similar to the European Union model of the European Food Safety Authority (EFSA).     

The organisation for economic cooperation and development

The global financial and economic crisis has prompted some scholars to suggest that a fundamental regulatory shift away from neoliberalism will take place – both in general and in the field of EU competition regulation. This paper shows that so far no radical break with the neoliberal type of competition regulation is heaving into sight. It sets out to explain this from the vantage point of a critical political economy perspective, which identifies the circumstances under which a crisis can result in a regulatory paradigm shift. Contrasting the current situation with the shift in EC/EU competition regulation after the crisis in the 1970s, the paper argues that the preconditions for a fundamental shift in this issue area are not present this time around. Several reasons account for this: the current crisis has been construed by economic and political elites as a crisis within and not of neoliberal capitalism; the social power configuration underpinning the neoliberal order remains unaltered; no clear counter-project has surfaced; the European Commission has been (and remains) in a position to oppose radical changes; and finally, there are no signs of a wider paradigm shift in the EU's regulatory architecture.     

Human resource management approaches in Spanish hotels: An introductory analysis

Although Spain is one of the most important tourism destinations in the world, Spanish tourism firms need to be more competitive in order to continue attracting citizens from other countries and human resource strategies can help. The present study aims to identify the specific human resource practices applied by hotels. The variables of interest are those related to human resource profile (number of employees, nationality and sex) and to human resource strategies (recruitment, hiring and training strategies). A survey of the hotel establishments in the Valencian Autonomous Region shows that a hard human resource approach prevails and that hotels apply the same human resource strategies regardless of their category or competitive strategy (universalistic approach).     

Co-breaking,cointegration, and weak exogeneity: Modelling aggregate consumption in Japan

This paper aims to estimate a parsimonious data-congruent model for aggregate real consumption in Japan using quarterly data over the past two decades. Testing co-breaking, cointegration and weak exogeneity plays an important role in pursuing the model reduction. It is demonstrated that co-breaking removes a deterministic shift caused by the collapse of the bubble economy in Japan in the early 1990s. Multivariate cointegration analysis then reveals that inflation plays a critical role in accounting for the long-run behaviour of the aggregate consumption. Further analysis finds that inflation and aggregate income are weakly exogenous with respect to a set of parameters of interest. Finally, a parsimonious data-congruent model for the aggregate consumption is estimated conditional on the set of weakly exogenous variables.