提前偿贷风险下催生次贷危机的微观主体行为分析——基于不完全信息动态博弈的视角

始于2007年的次贷危机所诱发的金融海啸席卷全球,当后危机时代逐渐走近之时,各种关于这场危机原因的探讨从宏观层面上作出了种种解释。但微观主体的理性决策行为与群体的不可预知性促使笔者从各参与主体的利益状况出发,采用博弈论的原理对次贷危机深层次的原因进行进一步的剖析。在不完全信息的假定下,本文从静态和动态两方面分别考察了贷款人、商业银行、投资者以及特定目的机构的收益函数,正是由于商业银行在贝叶斯均衡与序列均衡中都存在获利的可能,从而催生了整个证券化过程的展开。     

Organizing the Global Value Chain

We develop a property‐rights model of the firm in which production entails a continuum of uniquely sequenced stages. In each stage, a final‐good producer contracts with a distinct supplier for the procurement of a customized stage‐specific component. Our model yields a sharp characterization for the optimal allocation of ownership rights along the value chain. We show that the incentive to integrate suppliers varies systematically with the relative position (upstream versus downstream) at which the supplier enters the production line. Furthermore, the nature of the relationship between integration and “downstreamness” depends crucially on the elasticity of demand faced by the final‐good producer. Our model readily accommodates various sources of asymmetry across final‐good producers and across suppliers within a production line, and we show how it can be taken to the data with international trade statistics. Combining data from the U.S. Census Bureau's Related Party Trade database and estimates of U.S. import demand elasticities from Broda and Weinstein (2006), we find empirical evidence broadly supportive of our key predictions. In the process, we develop two novel measures of the average position of an industry in the value chain, which we construct using U.S. Input–Output Tables.     

零部件循环取货越库物流系统关键因子研究——仿真实验设计与分析方法

汽车和物流产业是国家重点扶持的两大振兴产业． 在众多汽车制造企业产能扩大的背景下,以零部件平均物流时间(cycle time,CT) 为绩效评价指标,深入研究了基于第三方物流的零部件循环取货越库物流模式( 简称 3PL－MRCD) 的优化设计问题． 建立了符合企业实际运作的离散系统随机仿真模型,即零部件循环取货与越库内部运作的集成模型． 与现有供应链仿真模型相比,由于存在较多的仿真因子,提出首先运用序贯分支法( sequential bifurcation, SB) 筛选 3PL－MRCD 系统关键因子,再应用响应面法(response surface methodology,RSM) 找到关键因子最优运作水平的方法步骤( SB－RSM) ,解决了大型仿真系统的优化设计问题． 基于调研的数据进行仿真实验,结果表明 SB－RSM 可准确找出影响CT的关键因子最优取值, 该值使CT达到较为理想的水平． 对大型仿真系统的优化而言,SB － RSM 比传统 RSM 更具实 验效率与效力,SB－RSM 为产能扩大3PL 物流决策的制定提供了可靠的解决方案,具有良好的应用价值．     

建设用地指标和建设用地的序贯拍卖定价机制研究

现行建设用地指标定价机制未能有效反映其真实价值,使得农民缺乏复垦闲置宅基地来提供建设用地指标的意愿。针对指标和建设用地的互补性特点,以及指标价值是开发商私人信息的特征,本文构建第一价格和第二价格两种密封拍卖下的互补品序贯拍卖模型,研究建设用地指标和建设用地的定价机制。理论和仿真分析得出两种拍卖下的建设用地指标和建设用地价格,并通过对比分析得出不同目标下的最优定价机制。研究发现,两种拍卖下,竞标人的建设用地指标报价均随着土地价格增值系数增加而提高,随着竞标人数递增而降低;序贯二价下的竞标人建设用地指标及建设用地的报价均高于序贯一价;序贯二价下,持有建设用地指标的竞标人获得建设用地的概率更高。因此,地方政府可采用适当提高土地闲置费用的方法,以此提高失地农民复垦权益,激励农民复垦闲置宅基地,增加建设用地指标供给;同时,采用序贯二价拍卖,提高建设用地指标和土地的利用效率。     

引入人脸抓拍系统还是升级安检设备？——有限资源下的地铁暴恐防御序贯博弈模型

在有限防御资源约束下,地铁安防部门面临着引进人脸抓拍系统构建二级地铁暴恐防御体系,还是升级原安检系统构建增强型一级地铁暴恐防御系统的选择。本文基于暴恐分子决策的目标价值依赖性和安防部门的接警反应时间不对称性,构建了有限资源下地铁暴恐防御策略选择的序贯博弈模型。得出并分析了双方的四种均衡策略,最后结合北京地铁积水潭站早高峰案例,给出了考虑高峰大客流冲击效应的暴恐防御决策建议。研究发现,当增强型安检系统的准确率过高,或接警反应时间有效率较高时,引进人脸抓拍系统策略占优,且人脸抓拍系统的社会价值对安防部门决策无直接影响。当增强型安检系统的准确率适中,或接警反应时间有效率较低时,第一种情况,在安防部门侧重效率的情况下,人脸抓拍系统的社会价值与安防效率正相关,引进人脸抓拍策略在其社会价值较高时占优;第二种情况,在侧重安全情况下,升级加强原安检系统策略占优,此时,人脸抓拍系统的社会价值对安防部门决策无影响。另外,较高的安检准确率将提升安检厅的乘客淤滞水平、强化高峰大客流对安检厅的冲击效应、削弱高峰大客流对候车厅的冲击效应,并最终拉升暴恐分子直接袭击安检厅的风险。     

A group sequential test for the inverse Gaussian mean

The present paper deals with the development of a group sequential test when response variable has an inverse Gaussian distribution with known scale parameter.     

On drift parameter estimation in models with fractional Brownian motion

We consider a stochastic differential equation involving standard and fractional Brownian motion with unknown drift parameter to be estimated. We investigate the standard maximum likelihood estimate of the drift parameter, two non-standard estimates and three estimates for the sequential estimation. Model strong consistency and some other properties are proved. The linear model and Ornstein–Uhlenbeck model are studied in detail. As an auxiliary result, an asymptotic behaviour of the fractional derivative of the fractional Brownian motion is established.     

Two-person sequential bargaining behavior with exogenous breakdown

We examine bargaining behavior in a noncooperative game in which players alternate in making and responding to proposals over the division of a given surplus. Although the number of bargaining periods is unlimited and time is not discounted, the bargaining is subject to exogenous breakdown at each period with a fixed probability which is common knowledge. We manipulate three probabilities of break-down in a between-subjects design that allows comparison with previous studies of two-person bargaining with time discounting. Assuming that subjects maximize expected utility, and this utility is measured by monetary payoffs, our results reject both the subgame perfect equilibrium and equal split solutions. Data analyses reveal that a substantial percentage of subjects behave adaptively in that they systematically search for the highest acceptable demands.     

Bayesian blinded sample size re-estimation

Information before unblinding regarding the success of confirmatory clinical trials is highly uncertain. Current techniques using point estimates of auxiliary parameters for estimating expected blinded sample size: (i) fail to describe the range of likely sample sizes obtained after the anticipated data are observed, and (ii) fail to adjust to the changing patient population. Sequential MCMC-based algorithms are implemented for purposes of sample size adjustments. The uncertainty arising from clinical trials is characterized by filtering later auxiliary parameters through their earlier counterparts and employing posterior distributions to estimate sample size and power. The use of approximate expected power estimates to determine the required additional sample size are closely related to techniques employing Simple Adjustments or the EM algorithm. By contrast with these, our proposed methodology provides intervals for the expected sample size using the posterior distribution of auxiliary parameters. Future decisions about additional subjects are better informed due to our ability to account for subject response heterogeneity over time. We apply the proposed methodologies to a depression trial. Our proposed blinded procedures should be considered for most studies due to ease of implementation.