Supply and pricing strategies of informal rural transport providers

Informal paratransit operators using a range of vehicle types (including pickup trucks, small buses, and motorcycles) are a major provider of mobility in rural areas of the developing world. The paper describes a mixed method approach used to examine such operators’ decisions about vehicle deployment, route frequency, network organisation, and pricing in three rural districts in South Africa. New evidence is presented showing that the condition of rural roads (both paved and unpaved) affects the quantity and quality of public transport services provided, as well as the fares charged to passengers. This strengthens the case for judicious infrastructure investment as a way of improving rural access and livelihoods, and suggests how this might happen by way of leveraging better private sector responses. We also describe the emergence of a differentiated service hierarchy involving a variety of vehicle types suited to different operating conditions, and based on intentional coordination among operators of minibus and pickup truck (‘bakkie’) services. We argue that governments should promote such coordination and innovation in rural transport markets.     

Micro-level stochastic loss reserving for general insurance

The vast literature on stochastic loss reserving concentrates on data aggregated in run-off triangles. However, a triangle is a summary of an underlying data-set with the development of individual claims. We refer to this data-set as ‘micro-level’ data. Using the framework of Position Dependent Marked Poisson Processes) and statistical tools for recurrent events, a data-set is analyzed with liability claims from a European insurance company. We use detailed information of the time of occurrence of the claim, the delay between occurrence and reporting to the insurance company, the occurrences of payments and their sizes, and the final settlement. Our specifications are (semi)parametric and our approach is likelihood based. We calibrate our model to historical data and use it to project the future development of open claims. An out-of-sample prediction exercise shows that we obtain detailed and valuable reserve calculations. For the case study developed in this paper, the micro-level model outperforms the results obtained with traditional loss reserving methods for aggregate data.     

欠发达地区城市群金融机构空间演化特征及影响因素——以中原城市群为例

基于国家企业信用信息登记系统的金融机构微观数据,综合运用NNI、Ripley’s K函数和空间热点聚类等方法,研究1998、2008、2018年中原城市群金融机构空间格局、集聚特征及热点分区,采用泊松回归模型研究中原城市群金融机构空间集聚的主要影响因素。研究发现:(1)中原城市群金融机构空间分布不均衡,金融机构总体和细分行业均呈现出显著的空间集聚特征。(2)空间集聚程度随着地理距离的增加先增强后减弱,金融机构的热点区主要集中在郑州—焦作—新乡和邯郸—邢台—安阳为核心的集聚区。(3)城乡居民储蓄是中原城市群金融机构集聚的核心影响因素,经济发展水平、对外交通联系、政府行为等因素的影响程度不断增强,人力资源、科技投入、对外开放水平的影响较弱。(4)作为内陆欠发达地区的城市群,中原城市群与其他城市群一致,作为高端服务业的金融业倾向于布局在高等级城市,但是由于经济发展水平和发展阶段的影响,其金融机构集聚的影响因素与其他城市群有较大差异。     

移动因特网不同流量下切换损失率研究

根据移动因特网中基本的硬切换和改进的半软切换算法时间流程仿真研究了 2种切换在泊松和自相似流量下的切换损失率。仿真数据表明 ,在网络负载均值相同的情况下 ,对于硬切换和半软切换 ,自相似流量的切换损失率要明显低于传统泊松流量 ,并通过分析泊松和自相似流量的概率密度函数尝试给出产生这一区别的原因。     

利用矩阵滤波技术估计信号二维波达方向

现有的基于子空间的波达方向估计算法都要求不相关信号源的数目小于阵元数目,但当信号源数目很多时,算法失效.为此,提出了一种具有过载估计能力的二维波达方向估计方法,先利用矩阵滤波技术接收数据进行预处理,使信号子空间限定在一个较小的区域内,把区域外的信号抑制掉,从而减小了有效的信号源数目,然后可以采用现有算法进一步估计二维波达方向.矩阵滤波器的设计过程也可以归结为一个最小二乘问题,效率很高.计算机仿真验证了算法的有效性.     

Trip Cultural Activities and Tourism Expenditure in Emerging Urban‐cultural Destinations

Although tourism expenditure is determined by different factors, the literature has not analysed the extent to which trip cultural activities affect tourism expenditure in the destination. The focus of this paper is a microeconomic analysis performed in 14 emerging urban‐cultural destinations in Andalusia (Spain). The results confirm that there are activities related to cultural visits, attendance at events or gastronomic activities that determine tourism expenditure. These results guide the implementation of specific actions by the policy‐makers in these destinations aimed at increasing the economic impact of tourism, based on the creation of high value‐added tourism products to overcome their mere dependence on built heritage. Copyright © 2015 John Wiley & Sons, Ltd.     

大型客运站客流分布规律研究

通过对客运站客流到达规律和出发规律进行深入分析,并通过对北京南站客流到发特性参数的现场调研和统计分析,得到北京南站到站与离站分布规律,为大型客运站的客流组织仿真奠定基础。     

A Globalized Conflict: European Anti-Jewish Violence during the Second Intifada

The globalization of the Arab–Israeli conflict during the period of the second intifada against Israel (from the autumn 2000 through at least the spring of 2005) has fostered anti-Jewish violence in Europe and throughout the world. With this globalized conflict as a context, this paper explores the effects of four explanatory factors on counts of anti-Jewish violence in 10 European countries. These factors are the relative sizes of a country’s Jewish and Muslim populations; how interpretations of the events in the Middle East mobilize the perpetrators; the unresponsiveness of bystanders; and the ambivalence of ordinary Europeans. Poisson multilevel models of the effects of these social structural and attitudinal variables suggest that all four factors contribute to violence. The violence counts include major attacks like shootings, knifings, bombings, and arson; and major violent incidents like vandalism and physical aggression without the use of a weapon. The views expressed in this paper are my own and do not necessarily reflect the opinions or policies of any organization to which I may be affiliated. I wish to thank Greg Maney and other reviewers of earlier versions of this paper for their helpful comments and Philip Gibbs of the SAS Institute for clarifying aspects of GLIMMIX.     

Back to the roots of the M/D/s queue and the works of Erlang, Crommelin and Pollaczek

A.K. Erlang introduced the M/D/ s queue in 1917, while F. Pollaczek and C.D. Crommelin formalized the theory using complex analysis and transforms. Let D ( s , λ ) denote the stationary probability of experiencing no waiting time in the M/D/ s queue with arrival rate λ and service requirement 1. We use D ( s , λ ) as a vehicle to give an overview of some of the results we obtained over the last years, including explicit characterizations of the roots, the derivation of infinite series from expressions in terms of roots using Fourier sampling and heavy-traffic limits obtained from square-root staffing. We propose to call D ( s , λ ) the Erlang D formula, for which several new results are presented and compared with the results of Pollaczek.     

Augmenting travel cost models with contingent behavior data

This paper proposes contingent behavior survey questions as a valuable supplement to observed data in travel cost models of non-market demand for recreational resources. A set of observed and contingent behavior results for each survey respondent allows the researcher to control for individual heterogeneity by taking advantage of panel data methods when exploring the nature of respondent demands. The contingent scenarios also provide opportunities to (a) test for differences between observed and contingent preferences and/or (b) assess likely demands under conditionsbeyond the domain of observed variation in costs or resource attributes. Most importantly, contingent scenarios allow the researcher to imposeexogenously varying travel costs. Exogenous imposition of travel costs together with panel methods reduces the omitted variables bias that plagues observed-data travel cost models of recreational demand. Using a convenience sample of data for illustrative purposes, we show how to estimate the demand for recreational angling by combining observed and contingent behavior data. We begin with simple naive pooled Poisson models and progress to more theoretically appropriate fixed effects panel Poisson specifications.The authors are at the University of Nevada and UCLA, respectively. We gratefully acknowledge the comments of both Scott Shonkwiler and participants in the W133 meetings in Santa Fe, New Mexico and for research material provided by Wayne Gray. The data were provided by Rang Narayanan. Research assistance was provided by Jerry McGraw and Natalie Tucker. Research partially supported by the Nevada Experiment Station. Any errors or omissions remain the authors' responsibility.