地震死亡人数预测与巨灾保险基金测算

巨灾保险制度在很大程度上依赖于巨灾损失的建模分析。由于巨灾损失通常存在极端值,一般的统计分布很难对其进行有效拟合。本文以我国大陆地区1950-2015年期间的地震灾害为研究样本,基于二维泊松过程建立了地震灾害死亡人数的预测模型。根据地震死亡人数的分布特征,将地震灾害分为非巨灾事件和巨灾事件,分别用右截断的负二项分布和右截断的广义帕累托分布拟合死亡人数;用齐次泊松过程描述地震灾害在给定期间的发生次数;用Panjer迭代法和快速傅里叶变换计算地震死亡人数在特定时期的分布以及风险度量值;用蒙特卡罗模拟法测算我国地震死亡保险基金的规模和纯保费水平。与传统的巨灾模型相比,本文提出的方法同时考虑了地震灾害发生的时间和地震死亡人数两个维度,并用贝叶斯方法估计模型参数,对地震死亡人数的拟合更加合理,为完善我国地震死亡保险提供了一种新的思路。     

真实固定效应空间随机前沿模型的贝叶斯估计

忽略个体效应和空间效应会严重干扰效率测算,其中忽略个体效应使得技术无效率项发生偏移,忽略空间相关性导致估计量有偏且不一致。本文基于真实固定效应随机前沿模型（引入了个体效应）,引入因变量和双边误差项的空间滞后项,构建了适用性更佳的真实固定效应空间随机前沿模型。对模型进行组内变化以消除额外参数,使用贝叶斯方法（需推导未知参数的后验分布并执行MCMC抽样）估计参数和技术效率。该方法真正克服了额外参数问题,比同类方法直观、简便。数值模拟结果表明,本文方法对参数、个体截距项及技术无效率项的估计精度均较高,且增加样本容量,估计精度变优。     

A bivariate distribution with Lomax and geometric margins

We develop a stochastic model describing the joint distribution of $(X,N)$, where $N$ has a geometric distribution while $X$ is the sum of $N$ dependent, heavy-tail Pareto components. Models of this form arise in many applications, ranging from hydro-climatology to finance and insurance. We present fundamental properties of this vector, including marginal and conditional distributions, moments, representations, and parameter estimation. We also include an example from finance, illustrating modeling potential of this new bivariate distribution.     

中国服务业的新经济地理特征

 利用2008年地级及以上城市层面服务业的汇总数据和2007年的城市数据,本文对影响服务业产业集聚的因素作了初步的考察,特别关注代表地区市场容量及与市场接近程度的城市市场潜能带来的影响。我们的分析表明,市场潜能较高的城市其服务业集聚程度也更高,平均来看,城市市场潜能提高1%,其服务业集聚程度提高0.2%左右。并且市场潜能对服务业集聚的影响在中部地区最为明显,东部地区次之,西部地区则不显著。市场潜能对服务业影响在地区间的差异可能与东部、中部、西部地区在城市体系以及地理位置的不同有关。本文还分析了其他城市特征及行业差异对服务业分布的影响。     

已知Gini相关系数对Copula函数上界的改进

如果已知Copula函数的某些信息,通常其Frechet-Hoeffding上下界则可以进一步收窄。R.B.Nelson分别在已知Kendall相关系数tau、Spearman相关系数rho、Blomqvist相关系数beta的条件下,给出了Copula函数的上下确界。鉴此,在给定Gini相关系数gamma的条件下,证明Copula函数的上界也可以进一步变窄,并给出上确界的表达式。     

Reshaping the Social: A Comparison of Fasu and Kubo-Febi Approaches to Incorporating Land Groups

In Papua New Guinea, local communities increasingly strive to render themselves ‘visible’ to the state as entities entitled to control and claim benefits from developments on their land. When people commit expressions of social form to paper they inevitably reshape previously operative social and political forms. This article compares ways in which two groups of Papua New Guineans have gone about the process of forming Incorporated Land Groups. Different histories of resource extraction, associated differences in engagement with state and companies and different pre-existing social forms are all reflected in the negotiations described. We discuss people's motivations for drawing up lists of members, the ways they went about this and implications for the communities themselves and for ILG registration more generally. Our analysis draws attention to how outcomes are shaped by scales of differentiation and emergent inequalities within the legal entities being imagined.     

Water Insecurity: A Case for Social Policy Action by Social Workers

Abstract

This article discusses the nationally and internationally urgent water insecurity issue, and why it represents a highly relevant area for social policy action by social workers, both at local and global levels. Drawing on secondary data analysis, the paper explores the nature and scope of water insecurity as a global social work issue, discusses its social policy dimensions, and suggests a framework for social policy action by social workers. It argues that, due to the complex nature of the water insecurity issue and its consequences, particularly on the poor and disadvantaged groups, and on ecosystems, it is critical to analyse it from conservation, distribution, and access perspectives and to act. Social workers need to think creatively about the application of their knowledge, skills, and virtues to the water insecurity issue in order to bring about necessary changes in human and institutional behaviour relating to water.     

Impossibility Results for Nondifferentiable Functionals

We examine challenges to estimation and inference when the objects of interest are nondifferentiable functionals of the underlying data distribution. This situation arises in a number of applications of bounds analysis and moment inequality models, and in recent work on estimating optimal dynamic treatment regimes. Drawing on earlier work relating differentiability to the existence of unbiased and regular estimators, we show that if the target object is not differentiable in the parameters of the data distribution, there exist no estimator sequences that are locally asymptotically unbiased or α‐quantile unbiased. This places strong limits on estimators, bias correction methods, and inference procedures, and provides motivation for considering other criteria for evaluating estimators and inference procedures, such as local asymptotic minimaxity and one‐sided quantile unbiasedness.     

Price Incentives and Coordination in a Two‐Product Decentralized Supply Chain

We investigate pricing incentives for competing retailers who distribute two variants of a manufacturer's product in a decentralized supply chain. Under a two‐dimensional Hotelling model, we derive decentralized retailers' prices for the products, and distortions in pricing when compared to centrally optimal prices. We show that price distortions decrease as consumers' travel cost between retailers increases, due to less intense competition. However, price distortions do not change monotonically in consumers' switching cost between products within stores. To fix decentralized retailers' price distortions, we construct a two‐part pricing contract that coordinates the supply chain. We show that the coordinating contract is Pareto‐improving and analyze increase in the supply chain profit under coordination.     

Distribution Channel Strategies for a Manufacturer with Complementary Products

In this article, we consider distribution channel strategies for an incumbent manufacturer who produces two complementary products and must determine whether or not to have another company to sell its products. We identify factors that affect the manufacturer's motivation to use dual‐channel distribution. Our results show that both complementarity between complements and product substitutability between firms influence the manufacturer's channel strategy. We find that if the potential entrant does not produce the complement of the primary product, a higher complementary effect for the complement will weaken the motivation of the incumbent to add an indirect channel. We also find that the incumbent has a stronger incentive to add the indirect channel when a product's substitutability is high. Furthermore, we show that when the two channels have the same pricing power, the incumbent has a stronger incentive to sell through the indirect channel in a higher pricing power environment.