Social distance,heterogeneity and social interactions

A crucial ingredient in social interaction models is the structure of peer groups, which link individuals with similar characteristics. We propose and study a dynamic binary choice model with social interactions in which heterogeneity of peer group effects is modeled introducing diversity in individual characteristics and linking pairwise influences to a social distance between individuals. Our framework allows for mimetic as well as anti-mimetic interactions and a heterogeneous structure of peer groups across individuals. Dynamic equilibria are studied in the limit when the number of agents is large. We show that the model exhibits multiple equilibria resulting from conflicts between various group pressures the individuals are subjected to. We study in particular the correlation in the population at equilibrium between the characteristics of the agents and their decisions: this quantity has an interesting empirical interpretation and solves a simple analytical equation when the number of agents is large. Finally we discuss the empirical content of the model and present a consistent estimator for the parameter describing which is consistent for any typical population regardless of the structure of individual characteristics.     

Living in an imaginary world that looks real

In the paper we show – using standard approaches, general equilibrium modeling and the assumption of complete rationality – that the macroeconomic environment is endogenous and is indeterminate. Specifically, it is argued – without resorting to sunspot type arguments – that microeconomic fundamentals do not suffice to characterize the economy at the macro level. In particular, we show how perceptions of rational agents of the workings of the economy (a) shape the environment, (b) affect the environment sufficiently to ensure that rational economic agents find the observed environment consistent with their beliefs even though it is not. As a by-product, we illustrate that endogenous macro uncertainty can arise as an outcome if rational economic agents whose expectations are anchored on endogenous variables expect them to arise. Finally, we show that systematic errors can persist indefinitely under rationality.     

Why do popular mechanisms lack efficiency in random environments?

We consider the problem of randomly assigning n indivisible objects to n agents. Recent research introduced a promising mechanism, the probabilistic serial that has superior efficiency properties than the most common real-life mechanism random priority. On the other hand, mechanisms based on Gale's celebrated top trading cycles method have long dominated the indivisible goods literature (with the exception of the present context) thanks to their outstanding efficiency features. We present an equivalence result between the three kinds of mechanisms, that may help better understand why efficiency differences among popular mechanisms might arise in random environments. This result also suggests that the probabilistic serial and the random priority mechanisms can be viewed as two top trading cycles based mechanisms that essentially differ in the initial conditions of the market before trading starts.     

板类冲压零件的特征参数描述及信息输入

本文就 CAPP 计算机辅助工艺设计零件信息描述进行了探讨,提出了用特征编码+参数列表的零件信息描述方法,达到了完整描述零件信息的目的。建立了一个以零件特征编码为主,以零件形状尺寸参数为辅,分层描述的零件信息建模与零件信息输入系统。     

Statistical analysis of change in networks

A survey is given of random graphs and random graph processes which can be used to describe and analyze networks that are changing with time. Marko-vian change over time, log-linear models for change, and conditionally uniform models for change are described. It is noted that estimation is usually complex if the random graph involves dependent dyads. Models with deterministic change over time may be a way to avoid the difficulties implied by dependent dyads. Logit regression methods are described that can be used to estimate such models.     

Absenteeism in the workplace: results from Danish sample survey data

Absentee data is analyzed using a worker environmental survey carried out in 1995. In a model which distinguishes between discretionary and involuntary absences individuals are assumed to maximize expected utility. This generates a probability distribution of days absent per year which is a mixture of two negative binomial distributions representing the behaviour of two unknown types of agent. This distribution is estimated separately for men and women. For each gender the number of days absent is quite small relative to what researchers have found in other countries. In the empirical model we identify different effects of the explanatory variables for workers with low rates of absenteeism and workers with high rates of absenteeism.     

Revealed stochastic preference: a synthesis

Summary. The problem of revealed stochastic preference is whether probability distributions of observed choices in a population for various choice situations are consistent with a hypothesis of maximization of preference preorders by members of the population. This is a population analog of the classical revealed preference problem in economic consumer theory. This paper synthesizes the solutions to this problem that have been obtained by Marcel K. Richter and the author, and by J. C. Falmagne, in the case of finite sets of alternatives, and utilizes unpublished research of Richter and the author to give results for the non-finite choice sets encountered in economic consumer theory.Received: 13 March 2003, Revised: 11 February 2004, JEL Classification Numbers: D1, C6.The preparation of this paper was supported by the E. Morris Cox endowment at the University of California, Berkeley. I am indebted to Robert Anderson, Salvador Barbara, Werner Hildenbrand, Rosa L. Matzkin, and Aviv Nevo for useful suggestions and comments. I am especially indebted to Marcel K. Richter, who was the source of many of the ideas and arguments contained in this paper.     

循环经济下的混合不确定闭环供应链协调控制研究

闭环供应链管理是循环经济极其重要的环节之一。本文根据大系统理论,在正向供应链和逆向供应链的基础上建立了闭环供应链协调控制结构。针对随机参数和模糊参数同时存在的情况,建立了含有混合不确定参数的闭环供应链协调控制模型,为系统研究混合不确定闭环供应链管理提供了新的思路,丰富了不确定规划的研究内容并为供应链管理运作提供了理论参考。     

Of songs and men: a model for multiple choice with herding

We propose a generic model for multiple choice situations in the presence of herding and compare it with recent empirical results from a Web-based music market experiment. The model predicts a phase transition between a weak imitation phase and a strong imitation, ‘fashion’ phase, where choices are driven by peer pressure and the ranking of individual preferences is strongly distorted at the aggregate level. The model can be calibrated to reproduce the main experimental results of Salganik et al. (Science, 311, 854–856 (2006)); we show in particular that the value of the social influence parameter can be estimated from the data. In one of the experimental situation, this value is found to be close to the critical value of the model.     

中国上市公司可转换债券非理性转股行为研究

以上海证券交易所上市的30只已进入转股期的可转换债券为样本研究,发现约58.5%的自愿转股行为违背了理性原则.用非参数回归分析法进行实证检验,发现市场流动性并不是影响非理性转股的因素,而隔夜风险、转股损失则是导致非理性转股行为发生的影响因素;投资者的心理因素对非理性转股具有非线性影响:历史收益率对投资者的影响取决于趋势信念和参考点两个因素.此外,非理性转股还受到框定依赖的影响,即当历史收益为正时,高的收益波动会增加非理性转股;而当历史收益为负时,高的收益波动会减少非理性转股.