Model selection in random effects models for directed graphs using approximated Bayes factors

With the development of an MCMC algorithm, Bayesian model selection for the p ₂ model for directed graphs has become possible. This paper presents an empirical exploration in using approximate Bayes factors for model selection. For a social network of Dutch secondary school pupils from different ethnic backgrounds it is investigated whether pupils report that they receive more emotional support from within their own ethnic group. Approximated Bayes factors seem to work, but considerable margins of error have to be reckoned with.     

面向3PL的物流信息系统的实现

以第三方物流企业的实际需求为例,给出了适合该第三方物流企业商业运作流程的物流信息系统整体解决方案,包括基于J2EE系统技术架构、系统功能、网络体系结构、系统接口等.该解决方案适用于目前大多数的第三方物流企业.     

R＆D项目影响因素的筛选及优化分析

影响R&D项目成败的因素是多种多样的,来自于方方面面。在实证调研的基础上建立了影响因素初选集,之后针对不同类型的因素,分别运用字2检验、T检验及因子分析的方法对初始因素集进行优化,为项目的评价工作建立更为科学、有效的指标体系。     

Strategic spin-offs of input divisions

When a downstream producer enters backward into the input market, a “helping the rivals effect” exists: Such entry hurts the firm's downstream business as it increases upstream competition and thus benefits its rival downstream firms. This negative externality prevents the newly-created upstream unit from expanding. A spin-off enables the firm to credibly expand in the input market, thereby forcing its upstream competitors to behave less aggressively. Spin-offs occur in equilibrium if and only if the number of downstream firms exceeds a threshold level. When there is more than one integrated firm, a spin-off by a firm can trigger spin-offs by others that would not occur otherwise.     

Critical factors in computing externalities for electricity resources

The New York State Environmental Externalities Cost Study and computerized externality model (EXMOD) are used to examine the specification of methods design and application factors in the computation of electricity externalities. We report the sensitivity of externality estimates with alternative specifications for 15 different factors in the analysis, including the selection of facility type, site, and operating characteristics; air emission assumptions and air modeling procedures; dose-response assumptions; economic valuation assumptions; and other modeling procedures and assumptions. Many of the factors that most influence externality computations can be well specified in the analysis, such as the facility type, age, characteristics, emission rates, whether there is SO₂ trading, and the inclusion of long range impacts. Most significant among the factors for which there remains significant scientific uncertainty are the selection and application of air dispersion models, selection of air pollution thresholds for health impacts, reduced life span risks associated with ozone exposure and with long-term exposure to PM₁₀, values for CO₂ damages, and the value to be applied to increased risks of reduced life span for individuals age 65 or older.     

IMF concern for reputation and conditional lending failure: Theory and empirics

In this paper we suggest that the dual role played by the IMF, as a creditor and as a monitor of economic reforms, might explain the lack of credibility of the Fund threat of sanctioning non-compliance with conditionality. Specifically, we show that the IMF's desire to preserve its reputation as a good monitor may distort its lending decisions towards some laxity. Moreover, such distortionary incentives may be exacerbated by the length of the relationship between a country and the Fund. Estimating a dynamic panel of 53 middle-income countries, for the period 1982–2001, we find that a longer relationship does increase IMF disbursements.     

Predation and mergers: Is merger law counterproductive?

This paper extends the literature on predation and mergers to a multi-firm setting. Two new arguments why predation is rational when a merger is an alternative are provided. First, predation is less prone to the free-rider problem, since mergers concentrate the costs of eliminating a rival with one firm, whereas predation allows the costs to be spread out. Second, predation can be profitable since it limits the negative effects of the bidding competition for the prey. It is also shown that a restrictive merger policy might be counterproductive by “helping” predators avoid the disadvantageous bidding competition for the prey.     

Distribution Dynamics of CO<Subscript>2</Subscript> Emissions

This paper uses nonparametric methods to examine the convergence in CO₂ emissions per capita on a sample of 100 countries for the period 1966–1996. Industrial countries show a convergence pattern. However, there is little evidence of convergence for the whole sample.     

Voting in assemblies of shareholders and incomplete markets

Summary. An economy with two dates is considered, one state at the first date and a finite number of states at the last date. Shareholders determine production plans by voting - one share, one vote - and at -majority stable stock market equilibria, alternative production plans are supported by at most percent of the shareholders. It is shown that a -majority stable stock market equilibrium exists if where S is the number of states at the last date and J is the number of firms. Moreover, an example shows that -majority stable stock market equilibria need not exist for smaller s.Received: 23 December 2002, Revised: 14 June 2004, JEL Classification Numbers: D21, D52, D71, G39. Correspondence to: Hervé CrésThe authors are grateful to an anonymous referee for helpful comments and suggestions. Financial support from the Danish Research Councils and hospitality of HEC is gratefully acknowledged by Mich Tvede and support from Fondation HEC is gratefully acknowledged by Hervé Crés.     

Intertemporal market division:: A case of alternating monopoly

In this paper, we report on an equilibrium with market dominance that exists in a simple two-firm model that features neither entry barriers nor sophisticated punishment strategies. This equilibrium induces an intertemporal market division in which the two firms alternate as monopolists - despite the fact that the model also sustains a Cournot duopoly. Even when initially both firms are active in the market, the alternating monopoly reveals itself rather quickly. Moreover, it Pareto dominates the Cournot equilibrium - as it is close to the cartel outcome. Several examples of what well may be such alternating monopolies are presented.