|
on Network Economics |
| By: | Giorgio Fagiolo; Tiziano Squartini; Diego Garlaschelli |
| Abstract: | In all empirical-network studies, the observed properties of economic networks are informative only if compared with a well-defined null model that can quantitatively predict the behavior of such properties in constrained graphs. However, predictions of the available null-model methods can be derived analytically only under assumptions (e.g., sparseness of the network) that are unrealistic for most economic networks like the World Trade Web (WTW). In this paper we study the evolution of the WTW using a recently-proposed family of null network models. The method allows to analytically obtain the expected value of any network statistic across the ensemble of networks that preserve on average some local properties, and are otherwise fully random. We compare expected and observed properties of the WTW in the period 1950-2000, when either the expected number of trade partners or total country trade is kept fixed and equal to observed quantities. We show that, in the binary WTW, node-degree sequences are sufficient to explain higher-order network properties such as disassortativity and clustering-degree correlation, especially in the last part of the sample. Conversely, in the weighted WTW, the observed sequence of total country imports and exports are not sufficient to predict higher-order patterns of the WTW. We discuss some important implications of these findings for international-trade models. |
| Date: | 2011–12 |
| URL: | http://d.repec.org/n?u=RePEc:arx:papers:1112.2895&r=net |
| By: | Mariya Aleksynska; Giovanni Peri |
| Keywords: | Migration, International Trade, Business Networks, Differentiated Goods |
| JEL: | F14 F16 F22 A A A |
| Date: | 2011–12 |
| URL: | http://d.repec.org/n?u=RePEc:cii:cepidt:2011-26&r=net |
| By: | Cabrales, Antonio; Calvo-Armengol, Antoni; Zenou, Yves |
| Abstract: | The aim of this paper is to provide a tractable model where both socialization (or network formation) and productive efforts can be analyzed simultaneously. This permits a fullfledged equilibrium/welfare analysis of network formation with endogenous productive efforts and heterogeneous agents. We show that there exist two stable interior equilibria, which we can Pareto rank. The socially efficient outcome lies between these two equilibria. When the intrinsic returns to production and socialization increase, all equilibrium actions decrease at the Pareto-superior equilibrium, while they increase at the Pareto-inferior equilibrium. In both cases, the percentage change in socialization effort is higher (in absolute value) than that of the productive effort |
| Keywords: | Peer effects; Network formation; Welfare; |
| JEL: | L22 L51 O31 O38 |
| Date: | 2011 |
| URL: | http://d.repec.org/n?u=RePEc:ner:carlos:info:hdl:10016/12914&r=net |
| By: | Tiziano Squartini; Diego Garlaschelli |
| Abstract: | In self-organizing networks, topology and dynamics coevolve in a continuous feedback, without exogenous driving. The World Trade Network (WTN) is one of the few empirically well documented examples of self-organizing networks: its topology strongly depends on the GDP of world countries, which in turn depends on the structure of trade. Therefore, understanding which are the key topological properties of the WTN that deviate from randomness provides direct empirical information about the structural effects of self-organization. Here, using an analytical pattern-detection method that we have recently proposed, we study the occurrence of triadic "motifs" (subgraphs of three vertices) in the WTN between 1950 and 2000. We find that, unlike other properties, motifs are not explained by only the in- and out-degree sequences. By contrast, they are completely explained if also the numbers of reciprocal edges are taken into account. This implies that the self-organization process underlying the evolution of the WTN is almost completely encoded into the dyadic structure, which strongly depends on reciprocity. |
| Date: | 2012–01 |
| URL: | http://d.repec.org/n?u=RePEc:arx:papers:1201.1215&r=net |
| By: | Dessi, Roberta (Toulouse School of Economics (IDEI and GREMAQ), and CEPR); Gallo, Edoardo (University of Oxford); Goyal, Sanjeev (University of Cambridge) |
| Date: | 2011–10 |
| URL: | http://d.repec.org/n?u=RePEc:ide:wpaper:25167&r=net |
| By: | G. WIMS; D. MARTENS; M. DE BACKER |
| Abstract: | Determining the risk of contagious failures due to credit exposures between organisations is a problem that has been the subject of a growing body of literature in recent years. The network model has become a commonly used tool, applied to both theoretical and empirical studies of financial contagion and systemic risk. The purpose of this paper is twofold. First, we propose a definition of the ‘Financial System Network’ which may be used to define the characteristics of any specific implementation of a network model in this field. Secondly, we evaluate the network models created by other researchers and compare and contrast various aspects of these implementations. We conclude by exploring avenues for future research in the area. |
| Date: | 2011–07 |
| URL: | http://d.repec.org/n?u=RePEc:rug:rugwps:11/730&r=net |
| By: | Daron Acemoglu; Vasco M. Carvalho; Asuman E. Ozdaglar; Alireza Tahbaz-Salehi |
| Date: | 2012–01–09 |
| URL: | http://d.repec.org/n?u=RePEc:cla:levarc:786969000000000359&r=net |
| By: | Pau Erola; Albert Diaz-Guilera; Sergio Gomez; Alex Arenas |
| Abstract: | Trade is a fundamental pillar of economy and a form of social organization. Its empirical characterization at the worldwide scale is represented by the World Trade Web (WTW), the network built upon the trade relationships between the different countries. Several scientific studies have focused on the structural characterization of this network, as well as its dynamical properties, since we have registry of the structure of the network at different times in history. In this paper we study an abstract scenario for the development of global crises on top of the structure of connections of the WTW. Assuming a cyclic dynamics of national economies and the interaction of different countries according to the import-export balances, we are able to investigate, using a simple model of pulse-coupled oscillators, the synchronization phenomenon of crises at the worldwide scale. We focus on the level of synchronization measured by an order parameter at two different scales, one for the global system and another one for the mesoscales defined through the topology. We use the WTW network structure to simulate a network of Integrate-and-Fire oscillators for six different snapshots between years 1950 and 2000. The results reinforce the idea that globalization accelerates the global synchronization process, and the analysis at a mesoscopic level shows that this synchronization is different before and after globalization periods: after globalization, the effect of communities is almost inexistent. |
| Date: | 2012–01 |
| URL: | http://d.repec.org/n?u=RePEc:arx:papers:1201.2024&r=net |
| By: | Sebastien Nouet (LEDa - Laboratoire d'Economie de Dauphine - Université Paris IX - Paris Dauphine); Jean Eric Pelet (LEMNA - Laboratoire d'économie et de management de Nantes Atlantique - Université de Nantes : EA4272); Ballantyne David (Centre for Relationship Marketing and Service Management - université d'Otago) |
| Abstract: | The purpose of this paper is to offer customer relationship insights in what is a fast developing new e-commerce development strategy. We examine the potential synergies between digital social networks (DSN) and e-commerce websites, thus bringing e-commerce and DSN websites into the same relational network orbit. A Delphi dialogical survey among ten DSN experts was arranged (five academics plus five web designers) to draw out from experts the degree of consensus currently existing between them on the strategies, competencies and resources needed for achieving effective DSN-website links. Our literature review allowed us to develop seven key themes, which were presented to our 10 DSN experts. Their evaluations were then obtained on a series of propositions within each of those themes, using a Delphi iterative review process. Convergence of expert opinion (and hence consensus) on each of these propositions emerged across four themes out of the seven presented. Results reveal the importance of firms obtaining good DSN technical expertise. Competencies of an ideal technical expert are defined but opinion diverged on how to find such skilled people in the short term. Thus a necessary but interim step in many firms may be the creation of dual roles for technical expertise and a network community (service) management. We conclude that our findings raise further questions for discussion; nonetheless it is clear that SME organizations can just as easily as large corporate enterprises outsource the development of the technical expertise necessary for the creation of effective DSN-ecommerce relationship links. |
| Keywords: | social networks, e-commerce, Facebook, Delphi method |
| Date: | 2011–12–25 |
| URL: | http://d.repec.org/n?u=RePEc:hal:wpaper:halshs-00655435&r=net |
| By: | Luca RICCETTI (Universit… Politecnica delle Marche, Dipartimento di Scienze Economiche e Sociali); Alberto RUSSO (Universit… Politecnica delle Marche, Dipartimento di Scienze Economiche e Sociali); Mauro GALLEGATI (Universit… Politecnica delle Marche, Dipartimento di Scienze Economiche e Sociali) |
| Abstract: | In this paper we build on the network-based financial accelerator model of Delli Gatti et al. (2010), modelling the firms' financial structure following the "dynamic trade-off theory", instead of the "pecking order theory". Moreover, we allow for multiperiodal debt structure and consider multiple bank-firm links based on a myopic preferred-partner choice. In case of default, we also consider the loss given default rate (LGDR). We find many results: (i) if leverage increases, the economy is riskier; (ii) a higher leverage pro-cyclicality has a destabilizing effect; (iii) a pro-cyclical leverage weakens the monetary policy effect; (iv) a Central Bank that wants to increase the interest rate, should previously check if the banking system is well capitalized; (v) policy maker has to develop the laws about bankruptcies to reduce the LGDR and improve the stability of banks. |
| Keywords: | Leverage, agent based model, bankruptcy cascades, dynamic trade-off theory, monetary policy |
| JEL: | C63 E32 E52 G01 |
| Date: | 2011–12 |
| URL: | http://d.repec.org/n?u=RePEc:anc:wpaper:371&r=net |
| By: | Stefanie Glotzbach (Sustainability Economics Group, Leuphana University of Lüneburg, Germany) |
| Abstract: | A twofold challenge arises from the normative aim of environmental justice to the management of agricultural systems: (1) the improvement of food security and livelihood of the rural poor today; (2) the sustenance and enhancement of the long-term productivity and resilience of agricultural systems to future generations. The paper analyzes the success factors and barriers of the Philippine farmer network MASIPAG in simultaneously realizing both objectives - based philosophically on Rawls’ “A Theory of Justice” (1971), conceptually on specific determinants of the relationship between the objectives, and empirically on the results of a comprehensive evaluation of the MASIPAG network. |
| Keywords: | environmental justice, ecosystem services, agriculture, agrobiodiversity, Philippines |
| JEL: | Q15 Q56 Q57 |
| Date: | 2012–01 |
| URL: | http://d.repec.org/n?u=RePEc:lue:wpaper:225&r=net |