Estimating rating transition probabilites with missing data

In this article we provide a rigorous treatment of one of the central statistical issues of credit risk management. GivenK-1 rating categories, the rating of a corporate bond over a certain horizon may either stay the same or change to one of the remainingK-2 categories; in addition, it is usually the case that the rating of some bonds is withdrawn during the time interval considered in the analysis. When estimating transition probabilities, we have thus to consider aK-th category, called withdrawal, which contains (partially) missing data. We show how maximum likelihood estimation can be performed in this setup; whereas in discrete time our solution gives rigorous support to a solution often used in applications, in continuous time the maximum likelihood estimator of the transition matrix computed by means of the EM algorithm represents a significant improvement over existing methods.     

提高企业组织执行力的有效途径

企业组织的执行力日益受到管理者和管理方法研究者的重视.本文采用系统的研究方法,从组织系统角度研究企业组织执行力.一种角度是从系统负效应的产生原因分析,另一种是把组织进行系统分类后进一步分析,从而从更深层次理解企业执行力状况,进而提高企业的竞争力.     

On Block Updating in Markov Random Field Models for Disease Mapping

Gaussian Markov random field (GMRF) models are commonly used to model spatial correlation in disease mapping applications. For Bayesian inference by MCMC, so far mainly single-site updating algorithms have been considered. However, convergence and mixing properties of such algorithms can be extremely poor due to strong dependencies of parameters in the posterior distribution. In this paper, we propose various block sampling algorithms in order to improve the MCMC performance. The methodology is rather general, allows for non-standard full conditionals, and can be applied in a modular fashion in a large number of different scenarios. For illustration we consider three different applications: two formulations for spatial modelling of a single disease (with and without additional unstructured parameters respectively), and one formulation for the joint analysis of two diseases. The results indicate that the largest benefits are obtained if parameters and the corresponding hyperparameter are updated jointly in one large block. Implementation of such block algorithms is relatively easy using methods for fast sampling of Gaussian Markov random fields ( Rue, 2001 ). By comparison, Monte Carlo estimates based on single-site updating can be rather misleading, even for very long runs. Our results may have wider relevance for efficient MCMC simulation in hierarchical models with Markov random field components.     

试论我国积极财政政策的挤出效应

本文运用宏观经济学关于财政政策挤出效应的理论 ,分别从需求现象和供给现象两方面分析了我国实施积极财政政策以来是否存在挤出 ,文章认为我国积极财政政策效应不明显的主要原因并非理论意义上挤出效应所致 ,而有其特殊的表现形式 ,这种特殊的表现形式与我国转轨时期的特定宏观环境有关。最后 ,文章分析了影响我国积极财政政策效应发挥的其他两点因素     

入世对中国教育的影响分析

入世将对中国教育目标、教育结构、教育产业、远程教育、高校研究与开发、人才流动、教育体制、教育市场和学校德育产生深远的影响。     

二元结构下城市化滞后效应及其成因分析

城市化滞后带来一系列的负面效应,分析其原因在于计划经济时期产生并延续下来的制度性二元结构。解决我国城市化滞后的根本途径是改革当前具有浓厚二元结构特征的各种政策制度,重构城乡联动发展的制度体系,走城乡一体化道路。     

论政府对会计监管的必要性、缺陷和效果

政府会计监管对纠正市场失灵、重新配置社会经济资源和调节经济运行有显著效果。同时 ,也存在严重缺陷 ,其表现为 :政府垄断会计规范制定权导致政府行为低效率 ;政府监管目标多元化导致政府角色冲突 ;政府会计监管部门行动不协调导致会计监管效率下降。政府会计监管要适度 ,监管不足和监管过度都是监管效果低下的表现。我国会计监管的现状是监管不足和监管过度两者并存     

水库地区路基的防护研究

当水库蓄水及运行过程中产生的库岸再造危及库区公路安全时，应对库岸或路基进行防护加固，在研究三峡、水口等水库塌岸历史、现状及预测的基础上，分析了岩质、土质和岩土混合岸坡的破坏方式、库岸再造类型，认为路基或库岸防护设计应遵循滑坡与塌岸综合治理、库岸防治与开发利用相结合、分时期分段落分水位区防护等原则，详细阐述了在不同库岸地质结构及库岸再造类型中采用的防护措施，研究了砌石坡式防护、防护林带、格构锚固、挡土墙、抗滑桩、喷锚等工程防护结构类型。     

取消农业税对农村牧区产生的影响

随着国家农业税全部免征政策的推行,农民税负大大减轻,但农民的其他隐性负担相应增加.同时,取消农业税对县乡财政收入产生影响,对农村经济也将产生深远影响.本文对巴彦淖尔市取消农业税后对农村牧区产生的影响进行了一些论述.     

钱谦益奉佛之前后因缘及其意义

钱钟书指斥钱谦益以明朝旧臣投靠清廷,借奉佛以“隐愧丧节”,论定牧斋昌言佞佛,非真奉佛,不过借佛门中人事以“浇块垒”、“自明衷曲”而已。此说并不周全,钱谦益生长于佛教气氛极浓厚之家庭,自其祖辈起,大都崇奉三宝,故钱谦益自童时即习知奉佛,亦常理中事。另外,其常熟宗族中与钱谦益至亲之顾氏、瞿氏及严氏,皆礼佛虔敬之甚。因此可知钱谦益入清前即奉佛,他并非借奉佛而隐瞒投清之隐情。钱谦益对时政之评论,往往于偈佛护法之文字中发微,其要义有三:人主之奉佛与否,与国运之盛衰密不可分;士大夫之谋人军师国邑者,应效佛门僧徒谋浮屠塔庙之诚;为重臣者,宜以明初文臣宋濂之以佛法事太祖为典范。