SELECTION BIAS IN SPATIAL ECONOMETRIC MODELS

ABSTRACT. The problem of spatial autocorrelation has been ignored in selection-bias models estimated with spatial data. Spatial autocorrelation is a serious problem in these models because the heteroskedasticity with which it commonly is associated causes inconsistent parameter estimates in models with discrete dependent variables. This paper proposes estimators for commonly-employed spatial models with selection bias. A maximum-likelihood estimator is applied to data on land use and values in 1920s Chicago. Evidence of significant heteroskedasticity and selection bias is found.     

INTERPRETING SPATIAL ECONOMETRIC ORIGIN‐DESTINATION FLOW MODELS

Spatial interaction or gravity models have been used to model flows that take many forms, for example population migration, commodity flows, traffic flows, all of which reflect movements between origin and destination regions. We focus on how to interpret estimates from spatial autoregressive extensions to the conventional regression‐based gravity models that relax the assumption of independence between flows. These models proposed by LeSage and Pace ( 2008 , 2009 ) define spatial dependence involving flows between regions. We show how to calculate partial derivative expressions for these models that can be used to quantify these various types of effect that arise from changes in the characteristics/explanatory variables of the model.     

TESTING THE SPATIAL SCALE AND THE DYNAMIC STRUCTURE IN REGIONAL MODELS (A CONTRIBUTION TO SPATIAL ECONOMETRIC SPECIFICATION ANALYSIS)*

This article addresses the problem of specification uncertainty in modeling spatial economic theories in stochastic form. It is ascertained that the traditional approach to spatial econometric modeling does not adequately deal with the type and extent of specification uncertainty commonly encountered in spatial economic analyses. Two alternative spatial econometric modeling procedures proposed in the literature are reviewed and shown to be suitable for analyzing systematically two sources of specification uncertainty, viz., the level of aggregation and the spatio-temporal dynamic structure in multiregional econometric models. The usefulness of one of these specification procedures is illustrated by the construction of a simple multiregional model for The Netherlands.     

USING EXPLANATORY SPATIAL MODELS IN PLANNING CONTEXTS (a reply)

The paper surveys a complex of challenges faced by the Ukrainian people in efforts to forge an independent Ukrainian state. These include charting an independent course within the new CIS, the allocation of former all-Union assets on Ukrainian territory, relations with minority ethnic groups (particularly Great Russians) in Ukraine, and potential territorial claims by neighboring states. Among economic problems faced by Ukrainian leaders are the need for reduced dependency upon energy imports, for structural change and renovation of aging industrial infrastructure, and for maintenance of favorable terms of trade with foreign countries and the former Soviet republics.     

中国省区间的外资R&D知识溢出及其空间差异研究——基于随机前沿生产模型(SFA)的实证

基于随机前沿生产函数构建的区域知识溢出模型,实证分析了中国省区层面的外资R&D空间溢出效应及其差异。结果显示,我国外资R&D活动不仅对本省存在溢出影响,对邻省亦有重要贡献;东部省区同时受益于其东、中部邻省的外资R&D溢出效应,但中西部省区均只从同一区域且邻近省份的外资R&D活动获益。研究还发现,我国三大区域内部均已结成紧密的省际空间联系,外资R&D双向溢出显著;但东部与中部省区的空间关联度不强,外资R&D呈单向溢出格局;而中部与西部之间目前仍存在明显的空间分割特征,造成彼此之间互无溢出。     

SITUATED KNOWLEDGE SPILLOVERS: A CASE STUDY OF INDUSTRY SPECIFICITY IN URBAN KNOWLEDGE SOURCING

Theorizing within the umbrella of evolutionary economic geography (EEG) has improved the understanding of how inter‐firm relatedness conditions knowledge spillovers, and how this affects the long‐term evolution of regions. Still, there are shortcomings in this approach associated with a quantitative and generic methodology, a static notion of relatedness, and a weakly developed policy and institutional perspective. In particular, there is a need for a better understanding of the mechanisms through which relatedness is developed and how policy affects existing and emerging relatedness. Certain mechanisms for knowledge transfer have been suggested, such as labour mobility, firm diversification, spin‐offs and social networks. But do the same mechanisms apply to all industries and in all territories, or are there specific mechanisms of knowledge sourcing at work in different contexts? To shed light on these questions, the article reports on a comparative case study of two knowledge‐intensive industries (life science and publishing) located in the Oslo metropolitan region. Based on a case study, the article suggests that both industries source knowledge through similar types of channels. However, despite similarities in how knowledge is accessed and absorbed in this diverse urban context, knowledge sourcing also seems to be conditioned by industry‐specific dynamics, policies and institutions.     

EXPLAINING THE VARIATION IN THE EMPIRICAL ESTIMATES OF ACADEMIC KNOWLEDGE SPILLOVERS*

ABSTRACT This paper presents a meta‐regression analysis of the empirical studies exploring the relationship between academic knowledge spillovers and regional innovation. The results of the literature are found to depend on country effects, the level of geographical aggregation employed, the method of measuring innovative output, the use of industry‐level data, and on the sectoral composition of the sample. Endogeneity, sample selection, and agglomeration forces are further elements that explain the findings on this issue but only weak evidence, after controlling for publication bias, supports the existence of a genuine spillover effect of university research on regional innovation.     

SPATIAL ECONOMETRIC MODELING OF ORIGIN‐DESTINATION FLOWS*

ABSTRACT Standard spatial autoregressive models rely on spatial weight structures constructed to model dependence among n regions. Ways of parsimoniously modeling the connectivity among the sample of N=n² origin‐destination (OD) pairs that arise in a closed system of interregional flows has remained a stumbling block. We overcome this problem by proposing spatial weight structures that model dependence among the N OD pairs in a fashion consistent with standard spatial autoregressive models. This results in a family of spatial OD models introduced here that represent an extension of the spatial regression models described in Anselin (1988) .     

ADDITIVE-INTERACTION MODELS OF SPATIAL AGGLOMERATION*

A wide variety of existing models of spatial agglomeration postulate additive-interaction effects among agents. In this paper, a synthesis of such models is achieved by establishing certain mathematical equivalences between them. In particular, it is shown that Rockafellar's conjugacy theory of concave functions yields a symmetric one-to-one correspondence between three classes of existing models, here designated as spatial-accessibility models, endogenous-contact models, and fixed-contact models. These correspondences not only allow the transference of results between models, but also suggest new economic interpretations of each model in terms of its conjugate model. A series of examples are drawn from the literature to illustrate these results.     

KNOWLEDGE SPILLOVERS,ABSORPTIVE CAPACITY,AND SKILL INTENSITY OF CHILEAN MANUFACTURING PLANTS*

ABSTRACT Knowledge spillovers are an important source of economic growth. In this study, we identify a mechanism through which knowledge spillovers occur among plants in the Chilean manufacturing industry. A plant‐level production function is estimated with the absorptive‐capacity hypothesis, that is, employment of skilled workers is a key channel through which knowledge is transmitted across plants. Results show that a plant's productivity from spillovers increases with its skill intensity, which is measured by the share of skilled workers in total employment. We also find that plants in a region with a large knowledge stock increase their skill intensity to benefit more from spillovers. Our results suggest that an increase in regional knowledge stock is the most effective policy to improve a plant's productivity. However, policies that encourage a plant to employ high skill‐intensive production also enhance its productivity.     

我国装备制造业的创新、知识溢出和产学研合作——基于一个扩展的知识生产函数方法

知识溢出的本地化现象揭示了地理边界的限制机理,然而越来越多的研究表明知识溢出也可发生在远距离的空间范围内。本文以我国装备制造业为例,采用扩展的知识生产函数方法探讨大学和科研机构的知识溢出对区域创新的影响。结果表明,大学和科研机构能够产生强烈的本地和跨区域的知识溢出效应,地理空间和创新网络在跨区域知识溢出中扮演重要角色。其中,产学研合作产生的知识溢出不仅局限于区域尺度,也发生在更高的国家尺度;在地理空间的制约影响下,高素质劳动力的流动对区域创新的影响十分显著且稳定,而大学和科研机构的衍生溢出机制则不那么明显,其原因可能与空间尺度选择有关。     

ROAD INVESTMENTS,SPATIAL SPILLOVERS,AND DEFORESTATION IN THE BRAZILIAN AMAZON*

ABSTRACT Understanding the impact of road investments on deforestation is part of a complete evaluation of the expansion of infrastructure for development. We find evidence of spatial spillovers from roads in the Brazilian Amazon: deforestation rises in the census tracts that lack roads but are in the same county as and within 100 km of a tract with a new paved or unpaved road. At greater distances from the new roads the evidence is mixed, including negative coefficients of inconsistent significance between 100 and 300 km, and if anything, higher neighbor deforestation at distances over 300 km.     

POISSON GRAVITY MODELS OF SPATIAL FLOWS*

ABSTRACT The purpose of this paper is to bring together a number of results on spatial flow models, and to reformulate them within a unified probability framework based on Poisson frequencies. To do so, a class of discrete stochastic processes, designated as independent flow processes, is developed which not only yields a complete characterization of Poisson flow frequencies, but also allows a wide range of gravity-type flow models to be formulated within this distributional framework. In particular, a hierarchical classification of 12 model types is developed, and each model type is shown to be characterizable directly in terms of behavioral axioms on independent flow processes.     

江苏省县域经济集聚和收敛的空间计量分析

通过探索性空间数据分析和空间计量分析方法,以实际人均GDP为测度指标,对江苏省65个县市的经济空间集聚、增长收敛性以及收敛机制进行讨论。研究发现1993-2009年实际人均GDP显示出越来越高的全局正相关,局部空间相关性也有增强的趋势。空间计量分析结果表明江苏省县域经济存在着β收敛,分时段研究为不同研究时段选择恰当的空间收敛模型后,收敛速度加快。技术扩散收敛机制和资本收敛机制分别在研究区间的前期和后期占主导作用,收敛机制的转变与江苏省在20世纪90年代末开始实行的区域协调发展政策密切相关。     

上海市就业市场状况与城市犯罪的空间计量分析

基于2008年上海市经济普查数据和城市犯罪数据,改变以往学者以失业率描述就业市场状况的做法,构建就业市场状况指数,并将其扩展到所有行业;同时,构建空间计量模型,研究上海市就业市场状况与刑事犯罪率之间关系,结果表明:1)就业市场状况对刑事犯罪率影响显著,不同行业的影响并不相同;其中,批发零售业、租赁和商业服务业、居民服务和其他服务业、公共管理和社会组织业就业的集中会引发犯罪活动的发生。2)空间计量模型在解释就业市场状况与刑事犯罪率之间关系时,计量效果良好。3)"空间效应"是影响刑事犯罪率的重要因素,其影响来自"空间邻近效应"和"空间误差效应"。     

INTERREGIONAL KNOWLEDGE SPILLOVERS AND OCCUPATIONAL CHOICE IN A MODEL OF FREE TRADE AND ENDOGENOUS GROWTH*

ABSTRACT A two region model of horizontal innovation with free trade and occupational choice is used to examine the spatial patterns of innovation and manufacturing industry in interior and core‐periphery long‐run equilibria. The inclusion of skill heterogeneity among workers creates a tension between stabilizing productivity effects that coincide with reallocations of workers across industries, and destabilizing productivity effects that arise with localized stocks of knowledge capital. We find that while core‐periphery equilibria are always saddlepath stable, interior equilibria are saddlepath stable when knowledge spillovers exceed a threshold level but are unstable otherwise. In addition, incorporating skill heterogeneity into the model allows for interior equilibria with asymmetric shares for innovation and industry.