违约损失率问题初探

巴塞尔新资本协议强调内部评级法在风险管理和资本监管中的重要作用。内部评级法的关键在于对违约率及其相关因素的测量,其中违约概率(PD)和违约损失率(LGD)是内部评级法的核心变量。对国际上关于LGD的表现及影响因素的讨论进行了总结与分析,并重点对LGD与PD之间的关系进行了介绍。     

Comparison of Hypothesis Testing and Bayesian Model Selection

The main goal of both Bayesian model selection and classical hypotheses testing is to make inferences with respect to the state of affairs in a population of interest. The main differences between both approaches are the explicit use of prior information by Bayesians, and the explicit use of null distributions by the classicists. Formalization of prior information in prior distributions is often difficult. In this paper two practical approaches (encompassing priors and training data) to specify prior distributions will be presented. The computation of null distributions is relatively easy. However, as will be illustrated, a straightforward interpretation of the resulting p-values is not always easy. Bayesian model selection can be used to compute posterior probabilities for each of a number of competing models. This provides an alternative for the currently prevalent testing of hypotheses using p-values. Both approaches will be compared and illustrated using case studies. Each case study fits in the framework of the normal linear model, that is, analysis of variance and multiple regression.     

基于Moran过程的PPP项目承包商机会主义行为演化动态

在PPP项目中,由于政府部门和承包商的目标不一致以及信息不对称等原因的存在,使得在其全寿命周期过程中,承包商的机会主义行为屡见不鲜。本文基于随机演化博弈理论,建构基于Moran过程的博弈模型,旨在探讨推动PPP项目承包商不采取机会主义行为策略的有利条件。研究表明,承包商数目不断扩大,通过降低承包商之间的举报成本,增大惩处力度,可使降低机会主义行为发生概率的效果显著。进一步,借助数值算例,对研究结果进行验证并给出相应的管理对策。     

Conditioning as disintegration

Conditional probability distributions seem to have a bad reputation when it comes to rigorous treatment of conditioning. Technical arguments are published as manipulations of Radon–Nikodym derivatives, although we all secretly perform heuristic calculations using elementary definitions of conditional probabilities. In print, measurability and averaging properties substitute for intuitive ideas about random variables behaving like constants given particular conditioning information.
One way to engage in rigorous, guilt-free manipulation of conditional distributions is to treat them as disintegrating measures—families of probability measures concentrating on the level sets of a conditioning statistic. In this paper we present a little theory and a range of examples—from EM algorithms and the Neyman factorization, through Bayes theory and marginalization paradoxes—to suggest that disintegrations have both intuitive appeal and the rigor needed for many problems in mathematical statistics.     

小蜂窝网络中基于速度估计的切换触发时间选择方案

在用户对系统带宽以及传输速率要求越来越严格的当下,小蜂窝技术成为解决室内和热点场景覆盖和容量问题的有效途径。为了缓解小蜂窝中切换失败率和乒乓切换率之间的矛盾,首先建立了小蜂窝网络场景下的切换模型,通过采用参考信号接收功率方案对用户终端（UE）的移动轨迹进行跟踪而达到速度估计的目的;之后,推导分析了该模型中切换失败概率、乒乓切换概率与切换触发时间、UE速度的关系;最后,采用遍历算法对切换触发时间进行优化选择。仿真结果表明,所提方案能够将切换失败概率降低到接近于零,同时将乒乓切换率降低了10%,很好地缓解了两者之间的矛盾,更适合于对乒乓切换敏感的高速移动UE。     

Econometric Analysis of Managers' Judgements on the Determinants of the Financial Situation in Russia

The paper presents an econometric analysis of the determinants of the financial situation in Russian manufacturing. Official statistics in Russia are not reliable. This is why the analysis is based on business opinion surveys carried out within `The Russian Economic Barometer' long-term research programme for monitoring and investigation of the transition to the market in Russia. The new adaptive approach elaborated by the author of the paper is used to form a correct set of explanatory variables in regression equations. This approach is based on the comparison of the forecast abilities of alternative models with different sets of explanatory variables. Two periods are considered and compared: January 1993 to January 1995 and February 1995 to January 1998. Two variables, the diffusion index of output and the average order-book level, provide the best explanation of the managers' judgement regarding the financial situation in Russia for the first period. It was found that for the second period, the influence of the `output index' diminished. The main factors with which managers related a `good' financial situation in their enterprises were the sample average of order-book level, the stocks of finished goods, the index of order-book level, the index of output prices ratio, and the indebtedness to banks. All relationships are presented in the context of linear probability and logit models.     

Computational suite of models with heterogeneous agents II: Multi-country real business cycle models

This paper describes the second model considered in the computational suite project that compares the performance of different numerical algorithms. It is a multi-country model in which countries face different productivity shocks. Solving such models is a challenging numerical problem unless the number of countries is small. The solutions are functions of a large set of arguments and the functional forms are unknown. Moreover, the solution procedures have to deal with high-dimensional integration problems.     

Conditional assessment of the impact of a Hausman pretest on confidence intervals

In the analysis of clustered and longitudinal data, which includes a covariate that varies both between and within clusters, a Hausman pretest is commonly used to decide whether subsequent inference is made using the linear random intercept model or the fixed effects model. We assess the effect of this pretest on the coverage probability and expected length of a confidence interval for the slope, conditional on the observed values of the covariate. This assessment has the advantages that it (i) relates to the values of this covariate at hand, (ii) is valid irrespective of how this covariate is generated, (iii) uses exact finite sample results, and (iv) results in an assessment that is determined by the values of this covariate and only two unknown parameters. For two real data sets, our conditional analysis shows that the confidence interval constructed after a Hausman pretest should not be used.     

计量模型中的加总偏误与内生性：一种数值模拟方法

理论文献已经证明了细分数据模型的内生性和加总过程产生的内生性是加总偏误的根本原因。但是由于内生性涉及误差项与回归量之间的相关性问题,试图通过实证方法审视这两类内生性对加总偏误的影响变得比较困难,而数值模拟却是一个较为理想的方法。在数值模拟中,我们通过控制随机变量的分布形式以及随机变量之间的相关程度,进而对两类内生性因素产生的加总偏误进行全面细致的考察。本文的研究将为加总偏误的内生性解释提供有力证据。     

Loan price modelling for local governments using risk premium analysis

Previous studies have highlighted the question of government loan interest as one of great current importance. Government borrowing levels are high, and reducing interest payments would generate savings to meet other spending needs and/or to lower taxation, thus supporting the sustainability of public finances. However, no previous study has presented a method for a local government to calculate its own credit risk and thus be in a position to negotiate lower interest rates on its borrowing. This article defines a financial model that enables local governments to estimate the interest rate payable on a bank loan, based on their credit risk premium, in accordance with the Basel II rules and the findings of our empirical study of large local governments.