Martijn J. Burger

On the Specification of the Gravity Model of Trade: Zeros, Excess Zeros and Zero-Inflated Estimation

Conventional studies of bilateral trade patterns specify a log-normal gravity equation for empirical estimation. However, the log-normal gravity equation suffers from three problems: the bias created by the logarithmic transformation, the failure of the homoscedasticity assumption, and the way zero values are treated. These problems normally result in biased and inefficient estimates. Recently, the Poisson specification of the trade gravity model has received attention as an alternative to the log-normality assumption (Santos Silva and Tenreyro, 2006). However, the standard Poisson model is vulnerable for problems of overdispersion and excess zero flows. To overcome these problems, this paper considers modified Poisson fixed-effects estimations (negative binomial, zero-inflated). Extending the empirical model put forward by Santos Silva and Tenreyro (2006), we show how these techniques may provide viable alternatives to both the log-normal and standard Poisson specification of the gravity model of trade.

Form follows function? linking morphological and functional polycentricity

Empirical research establishing the costs and benefits that can be associated with polycentric urban systems is often called for but rather thin on the ground. In part, this is due to the persistence of what appear to be two analytically distinct approaches in understanding and measuring polycentricity: a morphological approach centring on nodal features and a functional approach focused on the relations between centres. Informed by the oft-overlooked but rich heritage of urban systems research, this paper presents a general theoretical framework that links both approaches and discusses the way both can be measured and compared in a coherent manner. Using the Netherlands as a test case, it is demonstrated that most regions tend to be more morphologically polycentric than functionally polycentric. The difference is largely explained by the size, external connectivity and degree of self-sufficiency of a region’s principal centre.

Functional Polycentrism and Urban Network Development in the Greater South East, United Kingdom: Evidence from Commuting Patterns, 1981–2001

De Goei B., Burger M. J., Van Oort F. G. and Kitson M. Functional polycentrism and urban network development in the Greater South East, United Kingdom: evidence from commuting patterns, 1981–2001, Regional Studies. In contemporary literature on changing urban systems, it is often argued that the traditional central place conceptualization is outdated and should be replaced by a network view that emphasizes the increasing criss-crossing pattern of interdependencies between spatial units. This paper tests how urban networks develop by looking at commuting patterns in the Greater South East, United Kingdom, for the period 1981–2001. Although the empirical results indicate that the Greater South East cannot be currently characterized as a polycentric urban region or an integrated urban network, there is some evidence for urban network development at the local, intra-urban, level, and a decentralization of the system at the regional, inter-urban, level. De Goei B., Burger M. J., Van Oort F. G. et Kitson M. Le polycentrisme fonctionnel et le développement des réseaux urbains dans l’agglomération du sud-est du R-U: des preuves provenant de la structure des migrations quotidiennes entre 1981 et 2001, Regional Studies. Dans la documentation récente sur l’évolution des systèmes urbains, on affirme souvent que la notion classique de la place centrale est démodée et que l’on devrait la remplacer par une notion de réseaux qui souligne la croissance des interdépendances entrecroisées des zones géographiques. Cet article cherche à tester l’évolution des réseaux urbains tout en examinant la structure des migrations quotidiennes urbaines dans l’agglomération du sud-est du R-U entre 1981 et 2001. Bien que les résultats empiriques laissent voir que l’agglomération du sud-est du R-U ne se caractérise actuellement ni comme une région urbaine polycentrique, ni comme un réseau urbain intégré, il y a des preuves en faveur du développement des réseaux urbains sur le plan local intraurbain et d’une décentralisation du système au niveau régional interurbain. Royaume-Uni Agglomération du sud-est Réseaux urbains Migrations quotidiennes Modèle de gravité De Goei B., Burger M. J., Van Oort F. G. und Kitson M. Funktionaler Polyzentrismus und Entwicklung urbaner Netzwerke im Großraum des Südostens von Großbritannien: Belege aus Pendlerströmen, 1981–2001, Regional Studies. In der modernen Literatur über Veränderungen in den urbanen Systemen wird oftmals die These aufgestellt, dass die traditionelle Konzeptualisierung eines zentralen Ortes veraltet ist und durch eine Netzwerkperspektive ersetzt werden sollte, mit der die zunehmend kreuz und quer verlaufenden Wechselwirkungen zwischen räumlichen Einheiten betont wird. In diesem Beitrag überprüfen wir die Entwicklung urbaner Netzwerke am Beispiel der Pendlerströme im Großraum des Südostens von Großbritannien zwischen 1981 und 2001. Aus den empirischen Ergebnissen geht hervor, dass sich der Südosten Großbritanniens derzeit nicht als polyzentrische urbane Region oder integriertes urbanes Netzwerk charakterisieren lässt. Dennoch gibt es einige Anzeichen für die Entwicklung eines urbanen Netzwerks auf lokaler intra-urbaner Ebene sowie für eine Dezentralisierung des Systems auf regionaler intra-urbaner Ebene. Großbritannien Großraum Südost Urbane Netzwerke Pendlerverkehr Schwerkraftmodell De Goei B., Burger M. J., Van Oort F. G. y Kitson M. Policentrismo funcional y desarrollo de redes urbanas en el sureste de Inglaterra: evidencias de modelos de desplazamientos, 1981–2001, Regional Studies. En la literatura contemporánea sobre cambios en los sistemas urbanos se suele argumentar que la conceptualización tradicional de un lugar céntrico está desfasada y debería reemplazarse por una visión de redes que haga hincapié en el creciente modelo entrecruzado de interdependencias entre las unidades espaciales. En este artículo comprobamos cómo se desarrollan las redes urbanas al observar los modelos de desplazamientos en la región sureste del Reino Unido durante el periodo 1981–2001. Aunque los resultados empíricos indican que la región sureste del Reino Unido no se puede caracterizar actualmente como una región urbana policéntrica o una red urbana integrada, hay evidencias de un desarrollo de redes urbanas a nivel local e intraurbano y una descentralización del sistema a nivel regional e interurbano. Reino Unido Zona sureste Redes urbanas Desplazamientos al trabajo Modelo de gravedad

Social Context and network formation: an experimental study

Recently, there has been increasing interest in determining which social network structures emerge as a consequence of the conscious actions of actors. Motivated by the belief that “networks matter” in reaching personal objectives, it is a natural assumption that actors try to optimize their network position. Starting from the notion that an optimal network position depends on the social context, we examine how actors change their networks to reach better positions in various contexts. Distinguishing between three social contexts (a neutral context, a context in which closed triads are costly, and a context in which closed triads are beneficial), theoretical results predict that emerging networks are contingent on the incentives that are present in these contexts. Experiments are used to test whether networks that are theoretically predicted to be stable are also stable experimentally. We find that emerging networks correspond to a large extent with the predicted networks. Consequently, they are contingent on the incentives present in various social contexts. In addition, we find that subjects tend to form specific stable networks with a higher probability than predicted, namely, efficient networks and networks in which everyone is equally well off.

Polycentricity and the Multiplexity of Urban Networks

Abstract Empirical studies on polycentric urban regions (PURs) tend to analyse their spatial organization by examining only one type of functional linkage between cities. However, it has generally been accepted that urban networks are multiplex phenomena and that spatial interactions between cities can take many different forms, for example, commuting, shopping trips, and inter-firm trade. The spatial organization of each of these functional linkages is not necessarily identical, and, therefore, a region can appear to be polycentric and spatially integrated based on the analysis of one type of functional linkage but monocentric and loosely connected based on the analysis of another type of functional linkage. The aim of this paper is to stimulate further discussion on the multiplexity of urban networks with regard to the relational complexity of urban regions. Focusing on one PUR (Randstad Holland), we compare the geographical scope and spatial structure of different functional networks within it. Our results indicate that the spatial organization of the urban network depends on the lens through which it is assessed.

Borrowed Size, Agglomeration Shadows and Cultural Amenities in North-West Europe

Abstract It has been argued that the concept of “borrowed size” is essential to understanding urban patterns and dynamics in North-West Europe. This paper conceptualizes this idea and provides an empirical exploration of it. A place borrows size when it hosts more urban functions than its own size could normally support. A borrowed size for one place means that other places face an “agglomeration shadow” because they host fewer urban functions than they would normally support. This paper explores the extent to which size and function are related for places in North-West Europe and tries to explain why one place borrows size while the other faces an agglomeration shadow by examining the position of places within the regional urban system. The presence of urban functions was approximated using high-end cultural amenities. We conclude that the largest places in their functional urban area (FUA) are better able to exploit their own mass. The largest place in a FUA is also better able to borrow size from nearby places and from (inter)national urban networks than the lower-ranked places.

Regional and temporal variation in hysterectomy rates and surgical routes for benign diseases in the Netherlands

Abstract  Objective. To provide descriptive statistics on hysterectomy for benign gynecological conditions in the Netherlands and to analyze regional and temporal variations in hysterectomy rates and surgical routes. Design. Retrospective cohort study. Setting. Dutch hospitals. Population. All women with a hysterectomy for benign gynecological conditions in the Netherlands in 1995–2005. Methods. This study is based on an analysis of the Dutch registry of hospital admissions for 1995–2005. Main outcome measures. The age‐adjusted hysterectomy rate and age‐ and diagnosis‐adjusted proportion of vaginal hysterectomies for each Dutch healthcare region and time period. Results. The average annual crude hysterectomy rate for benign disease only, was 17.2 per 10 000 women of all ages. The vaginal route was chosen for 50.8% of the patients. During the study period, the number of hysterectomies for bleeding disorders declined almost 25%. Among 27 Dutch healthcare regions, the age‐adjusted hysterectomy rates for bleeding disorders and pelvic organ prolapse varied 2.2‐ and 2.3‐fold, respectively. The average annual age‐ and diagnosis‐adjusted proportion of vaginal hysterectomies varied from 43.4 to 63.8%. The regional differences with regard to rate and proportion declined slightly over time. Conclusions. The Netherlands is among the countries with the lowest hysterectomy rates and the highest proportion of vaginal hysterectomies. The regional differences indicate that a further decrease in the hysterectomy rates and an increase in the proportion of vaginal hysterectomies are possible.

The Geography of Global Corporate Networks: The Poor, the Rich, and the Happy Few Countries

The gradual integration of nations within our globalizing world is strongly related to the economic networks formed by multinational headquarters and their various subsidiaries located across the globe. Although the corporate reach of multinational corporations (MNCs) is clearly global, the geographical scope of their activities remains limited. Focusing on the network of ownership relations between the global Fortune 100 MNC headquarters and their subsidiaries, it is shown that global corporate activity remains unevenly distributed across the globe. Besides showing that richer countries are better connected within the global system than the poorer countries, the authors also reveal considerable differences in connectivity within the group of rich countries. Based on various determinants, these variations in network connectivity are explained.

The Geography of Chinese and Indian Greenfield Investments in Europe

Using a dataset of greenfield investments for the period of 1997-2008, the paper by three Dutch researchers seeks to determine to what extent Chinese and Indian foreign direct investment (FDI) in Europe is attracted to specific regional location factors. The authors utilize descriptive statistics and a negative binominal estimation method to analyze the number of greenfield investments, in an effort to explain why Chinese and Indian FDI is quite unevenly distributed across Europe. Support is marshaled for the hypothesis that Chinese and Indian FDI is more horizontal than vertical in character, and that divergence over time between current core European locations and more peripheral ones is increasing. Journal of Economic Literature, Classification Numbers: F210, O160, L200. 6 figures, 1 table, 54 references.

Stretching the concept of ‘borrowed size’

‘Borrowed size’ is an emerging policy concept in several European countries, presenting theoretical potential to explain contemporary urban dynamics unaddressed through conventional urban growth theories that emphasise the role of agglomeration economies. In its original conceptualisation by Alonso, the concept describes and explains the situation that especially smaller cities that are located in a larger ‘megapolitan complex’ do perform better because they have access to agglomeration benefits of larger neighbouring cities. This paper scrutinises the concept of borrowed size, thereby focusing on its conceptualisation and reviewing its empirical justification thus far. Our empirical analyses show that the concept must be stretched in terms of scale and scope to enhance its policy value. Borrowed size occurs when a city possesses urban functions and/or performance levels normally associated with larger cities. This is enabled through interactions in networks of cities across multiple spatial scales. These networks serve as a substitute for the benefits of agglomeration. Theoretically, the borrowed size concept demands a recasting of the geographical foundations of agglomeration theory.