Unit Roots,Level Shifts,and Trend Breaks in Per Capita Output: A Robust Evaluation

Determining whether per capita output can be characterized by a stochastic trend is complicated by the fact that infrequent breaks in trend can bias standard unit root tests towards nonrejection of the unit root hypothesis. The bulk of the existing literature has focused on the application of unit root tests allowing for structural breaks in the trend function under the trend stationary alternative but not under the unit root null. These tests, however, provide little information regarding the existence and number of trend breaks. Moreover, these tests suffer from serious power and size distortions due to the asymmetric treatment of breaks under the null and alternative hypotheses. This article estimates the number of breaks in trend employing procedures that are robust to the unit root/stationarity properties of the data. Our analysis of the per capita gross domestic product (GDP) for Organization for Economic Cooperation and Development (OECD) countries thereby permits a robust classification of countries according to the “growth shift,” “level shift,” and “linear trend” hypotheses. In contrast to the extant literature, unit root tests conditional on the presence or absence of breaks do not provide evidence against the unit root hypothesis.     

经济增速放缓与经济波动对居民福利影响的阶段差异分析

 本文基于中国1952-2007年时序数据定量研究经济增速放缓的福利损失和经济波动的福利损失,并侧重考察两种福利损失的大小关系在改革开放和经济体制改革目标确立前后的阶段差异。研究发现,无论是总体而言,还是在中国经济发展的不同阶段,经济波动的福利损失并不必然远小于经济增速放缓的福利损失,在相关参数的合理取值范围内,经济波动的福利损失大于经济增速放缓的福利损失是相当普遍的情形。因此,中国政府部门在重视长期经济增长的同时,不能草率否定短期经济稳定的重要性。     

农村居民消费增长比平稳更重要

 本文将消费习惯引入Lucas (1987)模型,采用农村五等份收入户的人均消费数据进行数值模拟,结果发现: 消费增长比消费平稳更重要,且收入等级越高,这种相对重要性就越突出。相对风险规避系数一定时,两类福利成本之比随习惯强度变化的轨迹呈倒U型; 习惯强度一定时,两类福利成本之比随相对风险规避系数的增大而递减。相对于其他等级的收入户,促进消费增长的经济政策为高收入户带来相对较多的福利,而平抑消费波动的经济政策能为低收入户带来较多的福利。因此,政府在促进农村居民消费增长的同时,也应重视消费波动给低收入群体造成的福利成本。     

Analysis of accelerated life tests with weibull failure distribution via generalized linear models

Efficient industrial experiments for reliability analysis of manufactured goods may consist in subjecting the units to higher stress levels than those of the usual working conditions. This results in the so called "accelerated life tests" where, for each pre-fixed stress level, the experiment ends after the failure of a certain pre-fixed proportion of units or a certain test time is reached. The aim of this paper is to determine estimates of the mean lifetime of the units under usual working conditions from censored failure data obtained under stress conditions. This problem is approached through generalized linear modelling and related inferential techniques, considering a Weibull failure distribution and a log-linear stress-response relationship. The general framework considered has as particular cases, the Inverse Power Law model, the Eyring model, the Arrhenius model and the generalized Eyring model. In order to illustrate the proposed methodology, a numerical example is provided.     

Supervisors’ Perception of Vicarious Trauma and Growth in Australian Refugee Trauma Counsellors

ABSTRACT

Vicarious trauma is a well-accepted phenomenon supported by more than 20 years of research, yet the body of research on the positive impact, known as vicarious post-traumatic growth, is relatively small. Based on a metasynthesis of qualitative peer-reviewed vicarious trauma studies, Cohen and Collens propose a model of the co-occurrence of vicarious trauma and vicarious post-traumatic growth. This model was examined through a qualitative study involving 11 interviews with supervisors of refugee trauma counsellors working in Forum of Australian Services for Survivors of Torture and Trauma (FASSTT) member agencies. This research project both reviewed the model from the perspective of experienced supervisors and illuminated what occurred within the supervision process to manage vicarious trauma and encourage vicarious post-traumatic growth. While the research project affirmed aspects of the model, the failure of the model to consider socio-political factors limited its applicability to FASSTT agencies.

IMPLICATIONS

• FASSTT clinical supervisors engage in supervision in a manner that may assist counsellors to process how their clients’ trauma disclosures impact on their levels of stress and change their perception of self, their role, and their worldview.

• Including recognition of the influence of the socio-political context of refugee trauma and trauma recovery may be an important additional component of supervision practice.

     

Spectral goodness of fit for network models

We introduce a new statistic, ‘spectral goodness of fit’ (SGOF) to measure how well a network model explains the structure of the pattern of ties in an observed network. SGOF provides a measure of fit analogous to the standard R² in linear regression. Additionally, as it takes advantage of the properties of the spectrum of the graph Laplacian, it is suitable for comparing network models of diverse functional forms, including both fitted statistical models and algorithmic generative models of networks. After introducing, defining, and providing guidance for interpreting SGOF, we illustrate the properties of the statistic with a number of examples and comparisons to existing techniques. We show that such a spectral approach to assessing model fit fills gaps left by earlier methods and can be widely applied.     

Latent Class Models in action: Bridging social capital & Internet usage

This paper explores how Latent Class Models (LCM) can be applied in social research, when the basic assumptions of regression models cannot be validated. We examine the usefulness of this method with data collected from a study on the relationship between bridging social capital and the Internet. Social capital is defined here as the resources that are potentially available in one’s social ties. Bridging is a dimension of social capital, usually related to weak ties (acquaintances), and a source of instrumental resources such as information. The study surveyed a stratified random sample of 417 inhabitants of Lisbon, Portugal. We used LCM to create the variable bridging social capital, but also to estimate the relationship between bridging social capital and Internet usage when we encountered convergence problems with the logistic regression analysis. We conclude by showing a positive relationship between bridging and Internet usage, and by discussing the potential of LCM for social science research.     

Modelling Variability in the Branching Structure of Strawberry Inflorescences

The branching structure of inflorescences of the cultivated strawberry ( Fragaria × ananassa Duch.) is very variable. This paper demonstrates that some aspects of this variability are well described by a simple stochastic model of branching that has two adjustable parameters. The model is shown to provide a good fit to data from a set of almost 700 inflorescences of the cultivar Elsanta, collected over two successive years. For one parameter the maximum likelihood estimator is a moment estimator which is fully efficient even if the detailed branching structure of the inflorescences is not recorded. This parameter provides a convenient summary of branching vigour. The maximum likelihood estimator of the second parameter must be determined iteratively and can be quite inefficient unless the full branching structure is recorded. The model demonstrates that branching structure is affected by the order in which inflorescences emerge on the plant.     

An Exploratory Analysis of the Value of the Skills of IT Personnel: Their Relationship to IS Infrastructure and Competitive Advantage

Determining and assessing the requisite skills of information technology (IT) personnel have become critical as the value of IT has risen in modern organizations. In addition to technical skills traditionally expected of IT personnel, softer skills like managerial, business, and interpersonal skills have been increasingly cited in previous studies as mandatory for these employees. This paper uses a typology of IT personnel skills—technology management skills, business functional skills, interpersonal skills, and technical skills—and investigates their relationships to two information systems (IS) success variables, IS infrastructure flexibility and the competitive advantage provided by IS. The study investigates these relationships using the perceptions of chief information officers (CIOs) from mostly Fortune 2000 companies. The contributions of this study are: IT personnel skills do affect IS success, technical skills are viewed as the most important skill set in affecting IS infrastructure flexibility and competitive advantage, and modularity is viewed as more valuable to competitive advantage than integration. Several explanations are offered for the lack of positive relationships between the softer IT personnel skills and the dimensions of IS success used in this study.     

转变经济增长方式的社会学思考——以“交易秩序”观考察中国经济发展模式

立足于为"十二五"规划建言献策,经由社会学结构功能论去论析为更好地理解与解决现时中国经济发展模式中的深层次矛盾与问题(如内需不足和社会分化),筑建社会学取向下以公民权利和政府责任臻善为愿景的社会建设路径是必要的,同时以经济社会学"交易秩序"理论为基本分析工具去论析实施此转变的缘由及其可能路径。