Schelling's spatial proximity model of segregation revisited

Schelling [Schelling, T.C., 1969. Models of Segregation. American Economic Review, Papers and Proceedings, 59, 488-493, Schelling, T.C., 1971a. Dynamic Models of Segregation. Journal of Mathematical Sociology, 1 (2), 143–186, Schelling, T.C., 1971b. On the Ecology of Micromotives. The Public Interest, 25, 61–98, Schelling, T.C., 1978. Micromotives and Macrobehavior. New York: Norton.] presented a microeconomic model showing how an integrated city could unravel to a rather segregated city, notwithstanding relatively mild assumptions concerning the individual agents' preferences, i.e., no agent preferring the resulting segregation. We examine the robustness of Schelling's model, focusing in particular on its driving force: the individual preferences. We show that even if all individual agents have a strict preference for perfect integration, best-response dynamics may lead to segregation. This raises some doubts on the ability of public policies to generate integration through the promotion of openness and tolerance with respect to diversity. We also argue that the one-dimensional and two-dimensional versions of Schelling's spatial proximity model are in fact two qualitatively very different models of segregation.     

Structural heterogeneity and proximity mechanism of China’s inter-regional innovation cooperation network

ABSTRACT

Based on the cooperation patent data between 31 provinces in China from 1985 to 2017, this paper portrays the topological structure, spatial pattern and proximity mechanism of China’s inter-regional innovation cooperation network by the graph theory, spatial statistical methods and the quadratic assignment procedure model. The conclusions are as follows: (1) the topological structure of China’s inter-regional innovation cooperation forms a hierarchical network with Beijing as the core and it exhibits a typical small-world property and ‘core–periphery’ structure. (2) In terms of spatial distribution characteristics, the ‘quadruple’ with the Beijing–Tianjin region, Yangtze River Delta, Pearl River Delta and Sichuan as the peaks has become the backbone of the inter-regional innovation cooperation network in China. At the same time, the spatial differentiation of the three indicators of degree centrality, median centrality and intensity centrality is obvious. (3) In terms of proximity mechanism, geographical, institutional and cognitive proximity exert a significant effect on China’s inter-regional innovation cooperation network linkage. However, there are significant differences in the effects of various proximity elements on China’s regional innovation network.     

In search of stars: Network formation among heterogeneous agents

This paper reports results from a laboratory experiment on network formation among heterogeneous agents. The experimental design extends the Bala–Goyal [Bala, V., Goyal, S., 2000. A non-cooperative model of network formation, Econometrica 68, 1131–1230] model of network formation with decay and two-way flow of benefits by introducing agents with lower linking costs or higher benefits to others. Furthermore, agents' types may be common knowledge or private information. In all treatments, the (efficient) equilibrium network has a “star” structure. While equilibrium predictions fail completely with homogeneous agents, star networks frequently occur with heterogeneous agents. Stars are not born but rather develop: with a high-value agent, the network's centrality, stability, and efficiency all increase over time. A structural econometric model based on best response dynamics and other-regarding preferences is used to analyze individual linking behavior. Maximum-likelihood estimates of the underlying structural parameters, obtained by pooling data from several treatments, allow us to explain the main treatment effects.     

Optimum commodity taxation in pooling equilibria

This paper extends the standard model of optimum commodity taxation (Ramsey, F., 1927. A Contribution to the Theory of Taxation. Economic Journal 37, 47–61; Diamond, P., Mirrlees, J., 1971. Optimal Taxation and Public Production, II: "Tax Rules". American Economic Review 61, 261–278) to a competitive economy in which markets are inefficient due to asymmetric information. Insurance markets are prime examples: consumers impose varying costs on suppliers but firms cannot associate costs with individual customers and consequently all are charged equal prices. In such a competitive pooling equilibrium, the price of each good is equal to the average of individual marginal costs weighted by equilibrium quantities. We derive modified Ramsey–Boiteux Conditions for optimum taxes in such an economy and show that, in addition to the standard formula, they include first-order effects which reflect the deviations of prices from marginal costs and the response of equilibrium quantities to the taxes levied. An explanation of the additional terms is provided. It is shown that a condition on the monotonicity of demand elasticities enables to sign the direction of the deviations from the standard case.     

A spatial analysis of R&D: the role of industry proximity

This paper employs individual firm data in order to check the existence of industry-spatial effects alongside other microeconomic determinants of R&D investment. Spatial proximity is defined by a measure of firms’ industry distance based on trade intensity between sectors. The spatial model specified here refers to the combined spatial-autoregressive model with autoregressive disturbances. In modelling the outcome for each location as dependent on a weighted average of the outcomes of other locations, outcomes are determined simultaneously. The results of the spatial estimation suggest that in their R&D decision firms benefit from spillovers originating from neighbouring industries.     

Racial segregation and the black–white test score gap

Racial segregation is often blamed for some of the achievement gap between blacks and whites. We study the effects of school and neighborhood segregation on the relative SAT scores of black students across different metropolitan areas, using large microdata samples for the 1998–2001 test cohorts. Our models include detailed controls for the family background of individual test-takers, school-level controls for selective participation in the test, and city-level controls for racial composition, income, and region. We find robust evidence that the black–white test score gap is higher in more segregated cities. Holding constant family background and other factors, a shift from a highly segregated city to a nearly integrated city closes about one-quarter of the raw black–white gap in SAT scores. Specifications that distinguish between school and neighborhood segregation suggest that neighborhood segregation has a consistently negative impact while school segregation has no independent effect, though we cannot reject equality of the two effects. Additional tests indicate that much of the effect of neighborhood segregation operates through neighbors' incomes, not through race per se. Data on enrollment in honors courses suggest that within-school segregation increases when schools are more highly integrated, potentially offsetting the benefits of school desegregation and accounting for our findings.     

Minimally acceptable altruism and the ultimatum game

I suppose that people react with anger when others show themselves not to be minimally altruistic. With heterogeneous agents, this can account for the experimental results of ultimatum and dictator games. Moreover, it can account for the surprisingly large fraction of individuals who offer an even split with parameter values that are more plausible than those that are required to explain outcomes in these experiments with the models of Levine [Levine, D.K., 1998. Modeling altruism and spitefulness in experiments. Review of Economic Dynamics 1, 593–622], Fehr and Schmidt [Fehr, E., Schmidt, K.M., 1999. A theory of fairness, competition and cooperation. Quarterly Journal of Economics 114, 817–868], Dickinson [Dickinson, D.L., 2000. Ultimatum decision making: a test of reciprocal kindness. Theory and Decision 48, 151–177] and Bolton and Ockenfels [Bolton, G.E., Ockenfels, A., 2000. ERC: a theory of equity, reciprocity, and competition. American Economic Review 90, 166–193].     

Validation in agent-based models: An investigation on the CATS model

In this paper we deal with some validation experiments on the complex adaptive trivial system (CATS) model proposed in Gallegati et al. [Gallegati, M., Giulioni, G., Palestrini, A., Delli Gatti, D., 2003a. Financial fragility, patterns of firms’ entry and exit and aggregate dynamics. Journal of Economic Behavior and Organization 51, 79–97; Gallegati, M., Delli Gatti, D., Di Guilmi, C., Gaffeo, E., Giulioni, G., Palestrini, A., 2005. A new approach to business fluctuations: heterogeneous interacting agents, scaling laws and financial fragility. Journal of Economic Behavior and Organization 56, 489–512]. In particular starting from a sample of Italian firms included in the AIDA database, we perform several ex post validation experiments over the simulation period 1996–2001. In the experiments, the model parameters have been estimated using actual data and the initial set up consists of a sample of agents in 1996. The CATS model is then simulated over the period 1996–2001. Using alternative validation techniques, the simulations’ results are ex post validated respect to the actual data.     

Some Reflections on the Spatial Dimensions of Occupational Segregation

This paper considers the role that urban spatial structure may play in the process of occupational segregation, and argues that neoclassical economic models of urban employment and residential location decisions have not considered the relationship between gender-based labor market status and space. The paper provides a critical feminist perspective on how conventional urban models have been used to explain patterns of segregation, and suggests reasons for limitations in existing theoretical and empirical analysis. It also explores ways in which economists can draw on work in other disciplines to develop fuller and more useful models of the relationship between urban spatial structure and occupational segregation.     

How well does a small structural model with sticky prices and wages fit postwar U.S. data?

In this paper, we ask whether a small structural model with sticky prices and wages, embedding various modelling devices designed to increase the degree of strategic complementarity between price-setters, can fit postwar U.S. data. To answer this question, we resort to a two-step empirical evaluation of our model. In a first step, we estimate the model by minimizing the distance between theoretical autocovariances of key macroeconomic variables and their VAR-based empirical counterparts. In a second step, we resort to Watson's [Watson, M.W., 1993. Measures of fit for calibrated models. Journal of Political Economy 101, 1011–1041.] procedure [Measures of fit for calibrated models. Journal of Political Economy 101 (6), 1011.1041] to quantify the model's goodness-of-fit. Our main result is that the combination of sticky prices and sticky wages is central in order to obtain a good empirical fit. Our analysis also reveals that a model with only sticky wages does not perform well according to Watson's criterion [Watson, M.W., 1993. Measures of fit for calibrated models. Journal of Political Economy 101, 1011–1041.].     

Credibility and endogenous societal discounting

We consider a dynamic moral hazard economy inhabited by a planner and a population of privately informed agents. We assume that the planner and the agents share the same discount factor, but that the planner cannot commit. We show that optimal allocations in such settings solve the problems of committed planners who discount the future less heavily than agents. Thus, we provide micro-foundations for dynamic moral hazard models that assume a societal discount factor in excess of the private one. We extend the analysis to allocations that are reconsideration-proof in the sense of Kocherlakota [Kocherlakota, N., 1996. Reconsideration-proofness: A refinement for infinite horizon time inconsistency. Games and Economic Behavior 15, 33–54]. We show that these allocations solve the choice problem of a committed planner with a unit discount factor.     

Segregation in Friendship Networks

We analyze a network‐formation model where agents belong to different communities. Both individual benefits and costs depend on direct as well as indirect connections. Benefits of an indirect connection decrease with distance in the network, while the cost of a link depends on the type of agents involved. Two agents from the same community always face a low linking cost, while the cost of forming a relationship between two agents from different communities diminishes with the rate of exposure of each of them to the other community. We find that socialization among the same type of agent can be weak even if the cost of maintaining links within one's own type is very low. Our model also suggests that policies aimed at reducing segregation are socially desirable only if they reduce the within‐community cost differential by a sufficiently large amount.     

基于三维距离的省域创新绩效空间溢出效应研究

运用空间计量模型对2010-2019年28个省份面板数据实证分析,研究省际创新绩效溢出效应空间格局,分析三维距离对省域创新绩效空间溢出影响,探索通过区域创新能力构建促进创新强省创新绩效正向空间溢出效应。研究发现：省域创新绩效由低向高增长阶段对邻近省域产生回流效应;在高位增长阶段,对空间邻接和地理距离邻近、经济水平差距大的省域具有回流效应;对空间邻接、地理距离邻近和经济距离邻近省域产生正向空间溢出效应。经济发展水平越接近,原始创新力对区域创新绩效溢出效应的促进越明显,且呈倒U型曲线趋势;经济水平差距是技术创新力直接效应与间接效应差距的关键因素;空间邻接和地理距离邻近是成果转化力空间正向溢出的关键因素。     

空间计量视角下创新网络结构资本对产业发展的影响测度

针对创新网络结构资本空间溢出如何影响产业发展的问题,基于地理邻近性和社会邻近性动态耦合视角,运用加权平均思想构建动态空间权重矩阵,并借助Moran′s I空间相关性检验、空间滞后（SLM）、空间误差（SEM）和空间杜宾（SDM）模型实验测度多元“地理-社会”邻近耦合下创新网络结构资本对产业发展的影响。以广西电子信息产业专利数据为例展开实证研究发现：①广西电子信息产业发展空间集聚效应明显,且地理邻近性作用大于社会邻近性;②广西电子信息创新网络结构资本空间溢出能够产生产业发展空间集聚效应;③广西电子信息创新网络结构资本通过直接和间接层次路径影响产业发展。研究结论可为产业创新空间（均衡）发展提供决策支持。     

Calibrating spatial models of trade

Empirical spatial models of trade that are based on a mathematical programming specification often exhibit a large discrepancy between the equilibrium solution and the observed demand, supply and levels of trade flows among countries. This discrepancy may be due to several causes. Assuming, however, that a trade model is not misspecified – in the sense that behavior of the economic agents involved in the specific commodity markets has been included in the study and that the relevant policy instruments have been properly taken into account – the cause of discrepancy may be traced either to imprecision of unit transaction costs or to imprecision in the measurement of the demand and supply functions' parameters, or both. Policy assessments based on this type of imprecise models are distorted. This paper presents a methodology for calibrating mathematical programming spatial trade models of increasing complexity, from the one-commodity case to a multi-commodity model with asymmetric slope matrices of demand and supply functions. The proposed calibration procedure identifies corrections of imperfectly measured parameters. The calibrated models generate solutions that exactly reproduce quantities produced and consumed in all countries, as well as trade flows among all pairs of countries, observed in a given base year. Such models may then serve as a springboard for assessing the impact of various policy changes on economic agents in the countries under study.     

Tax evasion and social interactions

The paper extends the standard tax evasion model by allowing for social interactions. In Manski's [Manski, C.F. (1993). Identification of Endogenous Social Effects: The Reflection Problem. Review of Economic Studies 60(3), 531–542.] nomenclature, our model takes into account endogenous interactions, i.e., social conformity effects, exogenous interactions, i.e., fairness effects, and correlated effects. Our model is tested using experimental data. Participants must decide how much income to report given individual and group tax rates and audit probabilities, and given a feedback on the other members' reporting behavior. Myopic and self-consistent expectations are considered in the analysis. In the latter case, the estimation is based on a two-limit simultaneous tobit with fixed group effects. A unique social equilibrium exists when the model satisfies coherency conditions. In line with Brock and Durlauf [Brock, W.A., Durlauf, S.N. (2001b). Interactions-Based Models, in J. Heckman and E. Leamer, eds., Handbook of Econometrics 5, Elsevier Science B.V., 3297–380.], the intrinsic nonlinearity between individual and group responses helps identify the model. Our results provide evidence of fairness effects but reject social conformity.     

Stackelberg financial-leader in insider trading model

In this paper, we extend the Jain-Mirman [Jain, N., & Mirman, L. (2000). Real and financial effects of insider trading with correlated signals. Economic Theory, 16, 333–353, Jain, N., & Mirman, L. (2002). Effects of insider trading under different market structures. The Quarterly Review of Economics and Finance, 42, 19–39] and the Daher-Mirman [Daher, W., & Mirman, L. (2006). Cournot duopoly and insider trading with two insiders. The Quarterly Review of Economics and Finance, 46, 530–551, Daher, W., & Mirman, L. (2007). Market structure and insider trading. International Review of Economics and Finance, 16, 306–331] papers on competition, and postulate that the competition among the insiders in the financial market be Stackelberg. However, an owner high in the organizational hierarchy, who designs manager compensation mechanisms and chooses a manager to serve his purpose, should have information on the manager's reaction and act as a Stackelberg leader in the financial sector. We show that owner's profit can definitely enlarged while the manager's profits may decrease or increase depending on the variances in the two sectors, which are the exogenous parameters.     

A note on optimal income taxation,public goods provision and robust mechanism design

This paper extends the model of optimal income taxation due to Mirrlees (Mirrlees, J., 1971. An exploration in the theory of optimum income taxation. Review of Economic Studies 38, 175–208) and includes private information on public goods preferences. A mechanism design approach is used to establish the following result: If policies are required to be robustly implementable in the sense of Bergemann and Morris (Bergemann, D., Morris, S., 2005. Robust mechanism design. Econometrica 73, 1771–1813), then the optimality conditions in the extended model with uncertainty about tax and expenditure policies are the same as in the standard model of optimal income taxation. The paper provides a foundation for a widely-used assumption in public finance, namely that individuals optimize their behavior subject to a predetermined and commonly known tax system.     

科技人才区域集聚为何不同——基于创新环境空间差异的解释

我国科技人才集聚具有地区差异性,并且与创新环境表现出明显的空间同位与同向演化特征,因此,从创新环境空间差异这一角度解释科技人才在区域集聚上的不同具有合理性。利用2010-2019年中国内地31个省（市、区）面板数据,通过构建空间杜宾模型考察区域创新环境对科技人才集聚的影响。结果表明：在全国总样本下,良好的区域创新环境显著促进本地区科技人才集聚,并对周围地区产生虹吸效应;在分样本情境下,地区创新环境对科技人才集聚的影响具有空间异质性,在东、中、西部地区,创新环境均对本地科技人才集聚产生不同程度的促进作用,其中,东部和中部地区创新环境的本地科技人才集聚作用最显著,西部地区相对较弱,同时,东部地区创新环境对邻近地区科技人才集聚具有显著虹吸效应,而中部地区和西部地区未有体现。据此,针对不同区域提出不同创新环境改善建议,以促进科技人才集聚。     

Should the north make unilateral technology transfers to the south?: North–South cooperation and conflicts in responses to global climate change

Whether developed countries should make unilateral technology transfers to developing countries in order to address global environment problems is debatable. This paper discusses the issue in a framework that recognizing nations' joint production of environmental externalities. Unlike the existing literature on unilateral transfers, this paper presents a North–South environmental–economic optimal growth model that allows transfers to mitigate externalities only. The paper derives criteria that would make such transfers feasible. By solving the transfer problem in a modified RICE model [Nordhaus, W.D., Yang, Z., 1996. A regional dynamic general equilibrium model of alternative climate change strategies, Am. Econ. Rev., 86 (4) 741–65], this paper also provides information on the timing and the amount of unilateral transfers from North to South to address potential global warming problem, one major global environmental externality. A policy implication from this study is that moderate employment of unilateral transfers would benefit North along with the world as a whole.