The Multilevel Approach to Repeated Measures for Complete and Incomplete Data

Repeated measurements often are analyzed by multivariate analysis of variance (MANOVA). An alternative approach is provided by multilevel analysis, also called the hierarchical linear model (HLM), which makes use of random coefficient models. This paper is a tutorial which indicates that the HLM can be specified in many different ways, corresponding to different sets of assumptions about the covariance matrix of the repeated measurements. The possible assumptions range from the very restrictive compound symmetry model to the unrestricted multivariate model. Thus, the HLM can be used to steer a useful middle road between the two traditional methods for analyzing repeated measurements. Another important advantage of the multilevel approach to analyzing repeated measures is the fact that it can be easily used also if the data are incomplete. Thus it provides a way to achieve a fully multivariate analysis of repeated measures with incomplete data. This revised version was published online in June 2006 with corrections to the Cover Date.     

金庸小说的主题学研究与定位——刘卫英、王立《金庸小说母题及中外比较研究》读后

《金庸小说母题及中外比较研究》一书,从多种母题、主题、意象来探讨金庸小说的民族文学特征、民族文化内蕴生成以及外来佛经故事影响。注意在一个武侠文学传统的传承性链条上,发掘金庸小说的多重文化价值。在具体母题、意象的实证探究中,非常重视主题学理论方法的运用,拓展了主题学研究的视阈与空间,进一步验证和提升了主题学研究方法的学术意义与价值。     

A mixture model for credit card exposure at default using the GAMLSS framework

The Basel II and III Accords propose estimating the credit conversion factor (CCF) to model exposure at default (EAD) for credit cards and other forms of revolving credit. Alternatively, recent work has suggested it may be beneficial to predict the EAD directly, i.e.modelling the balance as a function of a series of risk drivers. In this paper, we propose a novel approach combining two ideas proposed in the literature and test its effectiveness using a large dataset of credit card defaults not previously used in the EAD literature. We predict EAD by fitting a regression model using the generalised additive model for location, scale, and shape (GAMLSS) framework. We conjecture that the EAD level and risk drivers of its mean and dispersion parameters could substantially differ between the debtors who hit the credit limit (i.e.“maxed out” their cards) prior to default and those who did not, and thus implement a mixture model conditioning on these two respective scenarios. In addition to identifying the most significant explanatory variables for each model component, our analysis suggests that predictive accuracy is improved, both by using GAMLSS (and its ability to incorporate non-linear effects) as well as by introducing the mixture component.     

人口老龄化会导致中国劳动力就业极化吗？

基于我国2000—2021年的省级及八大综合经济区的面板数据,实证检验人口老龄化对劳动力就业结构的极化效应。研究发现：人口老龄化促进低、高技能劳动力就业比重提高,同时降低中等技能劳动力就业比重,导致劳动力就业结构整体上呈现“两端极化”特征,且这一调整过程随着老龄化加剧呈现倒U形趋势。分八大综合经济区来看,东部沿海经济区的老龄化对劳动力就业结构的影响方向与全国样本一致且更敏感;南部经济区的老龄化促进高技能劳动力就业呈“单向极化”特征;大西南经济区的老龄化促进低技能劳动就业呈“单向极化”特征。进一步门槛检验发现,随着人均收入水平的提高,老龄化对劳动力就业“两端极化”效应存在明显的双重门槛特征,且表现出增益效果。     

桥头跳车的病害机理及对策——以柳州市三门江大桥为例

文章结合柳州市三门江大桥桥台的施工实践，通过对桥头出现跳车的原因及病害机理进行分析，从桥头的勘察、设计、施工等角度，提出了预防和治理桥头跳车这一常见病害的一些有效措施。     

CONSTANT PROPORTION PORTFOLIO INSURANCE IN THE PRESENCE OF JUMPS IN ASSET PRICES

Constant proportion portfolio insurance (CPPI) allows an investor to limit downside risk while retaining some upside potential by maintaining an exposure to risky assets equal to a constant multiple of the cushion , the difference between the current portfolio value and the guaranteed amount. Whereas in diffusion models with continuous trading, this strategy has no downside risk, in real markets this risk is nonnegligible and grows with the multiplier value. We study the behavior of CPPI strategies in models where the price of the underlying portfolio may experience downward jumps. Our framework leads to analytically tractable expressions for the probability of hitting the floor, the expected loss, and the distribution of losses. This allows to measure the gap risk but also leads to a criterion for adjusting the multiplier based on the investor's risk aversion. Finally, we study the problem of hedging the downside risk of a CPPI strategy using options. The results are applied to a jump-diffusion model with parameters estimated from returns series of various assets and indices.     

展会活动随机事件的预判和处理

展会活动的组织和实施过程中,随机事件层出不穷,如何准确地对这些随机事件进行预判,并及时采取得当的措施进行防范和处理,是对展会组织者的组织水平和能力的真正考验。基于对这个问题的关注,通过对一些具体问题的分析为业内同行提供一些有益的参考,使得展会的组织更加便利,展会经济活动的效率更高、风险更小。     

Equilibrium prices in a random exchange economy with dependent agents

Summary. This paper presents a model of a Walrasian exchange economy in which the preferences and endowments of the agents are random. Stochastic interaction among the agents is formally described in terms of dependency neighborhoods. The main result is a characterization of the distribution of market-clearing prices in a large economy. Received: April 23, 1999; revised version: May 6, 1999     

把握基层管理者执行力提升的关节点

基层管理者的执行力大小直接关系到组织的成败得失,并反映了组织人力资源管理的绩效情况.基层管理者要提高执行力,必须明确目标并制定行动计划,充分认识本组织的资源优势并加以优化配置,协调好本组织与相关组织、上级组织和下级组织之间的关系,让员工拥有梦想,努力将"中游水平"整体提升.     

北部湾城市群基础设施与经济协调发展研究

本文从基础设施的不同功能出发,以经济性、生活性、社会性来划分北部湾地区城市群的基础设施指标,运用VAR模型实证分析了1990～2009年北部湾城市群基础设施与经济发展之间的关系。结果表明,经济增长与基础设施之间有正向协整关系,其中社会性和经济性基础设施对经济增长显示正向协整关系,生活性基础设施与经济增长是负向协整关系。