nep-net New Economics Papers
on Network Economics
Issue of 2022‒08‒08
thirteen papers chosen by
Alfonso Rosa García
Universidad de Murcia

  1. Clustering coefficients as measures of the complex interactions in a directed multiplex network By Paolo Bartesaghi; Gian Paolo Clemente; Rosanna Grassi
  2. The Fragility of Urban Social Networks - Mobility as a City Glue - By Pierre Magontier, Maximilian v. Ehrlich, Markus Schläpfer
  3. Equilibria in Network Constrained Energy Markets By Leonardo Massai; Giacomo Como; Fabio Fagnani
  4. Peer effects, self-selection and dishonesty By Liza Charroin; Bernard Fortin; Marie Claire Villeval
  5. nwxtregress: Network regressions in Stata By William Grieser; Morad Zekhnini; Jan Ditzen
  6. The Exports of Knowledge Intensive Services. A Complex Metric Approach By Leogrande, Angelo; Costantiello, Alberto; Laureti, Lucio
  7. Travel time reliability in transportation networks: A review of methodological developments By Zhaoqi Zang; Xiangdong Xu; Kai Qu; Ruiya Chen; Anthony Chen
  8. Social media charity campaigns and pro-social behavior. Evidence from the Ice Bucket Challenge By Andrea Fazio; Francesco Scervini; Tommaso Reggiani
  9. A multi-operator differentiated transport network model By Jolian McHardy
  10. Diffusion of Innovation over Social Networks under Limited-trust Equilibrium By Vincent Leon; S. Rasoul Etesami; Rakesh Nagi
  11. Spatial network analysis of container port operations: the case of ship turnaround times By César Ducruet; Hidekazu Itoh
  12. Defence partnerships, military expenditure, investment, and economic growth: an analysis in PESCO countries By Karamanis, Dimitris
  13. Dynamics of couplings and their implications in inter-organizational multi-actor research and innovation projects By Svetlana Klessova; Sebastian Engell; Catherine Thomas

  1. By: Paolo Bartesaghi; Gian Paolo Clemente; Rosanna Grassi
    Abstract: In this paper, we propose new definitions of clustering coefficient for weighted and directed multiplex networks. We extend in the multiplex framework the formulas of clustering coefficients existing in the literature for weighted directed monoplex networks. We quantify how deep a node is involved in a cohesive structure focusing on a single layer, all layers or the entire system, respectively. The coefficients capture various features intrinsically related to the complex topology of the multiplex network. We test their effectiveness applying them to a particularly complex structure such as the international trade network. The trade data integrate different aspects and they can be described by a directed and weighted multiplex network, where each layer represents import and export relationships between countries for a given sector. The proposed coefficients find successful application in describing the interrelations of the trade network, allowing to disentangle the effects of countries and sectors and jointly consider the interactions between them.
    Date: 2022–06
  2. By: Pierre Magontier, Maximilian v. Ehrlich, Markus Schläpfer
    Abstract: Social interactions are crucial to a city's cohesion, and the high frequency of interaction reflects many benefits of density. However, adverse environmental conditions, such as pollution or pandemics, may critically affect these interactions as they shift preferences over meeting locations and partners. Some interactions may be shifted to the virtual space, while other non-planned interactions may disappear. We analyze spatial interaction networks in Singapore covering about half of the adult population at a fine-grained spatial resolution to understand the importance of population mixing and places' amenities for urban network resilience. We document that environmental shocks negatively affect total interactions. Still, conditional on meeting physically, the number and type of location options may crucially impact the intensity and type of social interactions. The interplay between preferences for meetings partners, locations, and mobility determines population mixing and the fragility of urban social networks.
    Keywords: Urban interactions, networks, mobility, environmental shocks
    JEL: R1 R2 L14
    Date: 2022–07
  3. By: Leonardo Massai; Giacomo Como; Fabio Fagnani
    Abstract: We study the equilibrium state of an energy market composed of producers who compete to supply energy to different markets and want to maximize their profits. The energy market is modeled by means of a graph that represents a constrained power network where nodes represent the markets and links are the physical lines with a finite capacity connecting them. Producers play a networked Cournot game on such a network together with a centralized authority, called market maker, that facilitates the trade between geographically separate markets via the constrained power network and aims to maximize a certain welfare function. We study existence of uniqueness of the Nash equilibria and prove a connection between capacity bottlenecks in the power network and the emergence of price differences between different markets that are separated by bottlenecked lines.
    Date: 2022–06
  4. By: Liza Charroin (CES - Centre d'économie de la Sorbonne - UP1 - Université Paris 1 Panthéon-Sorbonne - CNRS - Centre National de la Recherche Scientifique); Bernard Fortin (ULaval - Université Laval [Québec]); Marie Claire Villeval (GATE Lyon Saint-Étienne - Groupe d'analyse et de théorie économique - ENS Lyon - École normale supérieure - Lyon - UL2 - Université Lumière - Lyon 2 - UCBL - Université Claude Bernard Lyon 1 - Université de Lyon - UJM - Université Jean Monnet [Saint-Étienne] - Université de Lyon - CNRS - Centre National de la Recherche Scientifique, IZA - Forschungsinstitut zur Zukunft der Arbeit - Institute of Labor Economics)
    Abstract: If individuals tend to behave like their reference group, is it because of peer effects, selfselection, or both? Using a peer effect model allowing for conformity and link formation, we designed a real-effort laboratory experiment in which individuals could misreport their performance and select their peers. Our results reveal both a preference for conformity and homophilous link formation, but only among individuals cheating in isolation. This suggests that such link formation was not motivated by a taste for similarity but by acquiring self-serving information. Importantly, we reject the presence of a self-selection bias in the peer effect estimates by showing that the size of peer effects is similar when identical peers were randomly assigned and when individuals selected them.
    Keywords: Peer effects,Self-selection,Homophily,Dishonesty,Experiment
    Date: 2022
  5. By: William Grieser (Texas Christian University); Morad Zekhnini (Michigan State University); Jan Ditzen (Free University of Bozen-Bolzano)
    Abstract: Network analysis has become critical to the study of social sciences. While several Stata programs are available for analyzing network structures, programs that execute regression analysis with a network structure are currently lacking. We fill this gap by introducing the nwxtregress command. Building on spatial econometric methods (LeSage and Pace 2009), nwxtregress uses MCMC estimation to produce estimates of endogenous peer effects, as well as own-node (direct) and cross-node (indirect) partial effects, where nodes correspond to cross-sectional units of observation, such as firms, and edges correspond to the relations between nodes. Unlike existing spatial regression commands (for example, spxtregress), nwxtregress is designed to handle unbalanced panels of economic and social networks as in Grieser et al. (2021). Networks can be directed or undirected with weighted or unweighted edges, and they can be imported in a list format that does not require a shapefile or a Stata spatial weight matrix set by spmatrix. Finally, the command allows for the inclusion or exclusion of contextual effects. To improve speed, the command transforms the spatial weighting matrix into a sparse matrix. Future work will be targeted toward improving sparse matrix routines, as well as introducing a framework that allows for multiple networks.
    Date: 2022–06–10
  6. By: Leogrande, Angelo; Costantiello, Alberto; Laureti, Lucio
    Abstract: In the following article, the value of the "Knowledge Intensive Services Exports in Europe" in 36 European countries is estimated. The data were analyzed through a set of econometric models or: Poled OLS, Dynamic Panel, Panel Data with Fixed Effects, Panel Data with Random Effects, WLS. The results show that “Knowledge Intensive Services Exports” is negatively associated, among others, with "Buyer Sophistication", "Government Procurement of Advanced Technology Products", and positively associated with the following variables i.e. "Innovation Index", "Sales Impacts" and "Total Entrepreneurial Activity". Then a clusterization with k-Means algorithm was made with the Elbow method. The results show the presence of 3 clusters. A network analysis was later built and 4 complex network structures and three structures with simplified networks were detected. To predict the future trend of the variable, a comparison was made with eight different machine learning algorithms. The results show that prediction with Augmented Data-AD is more efficient than prediction with Original Data-AD with a reduction of the mean of statistical errors equal to 55,94%.
    Keywords: Innovation, and Invention: Processes and Incentives; Management of Technological Innovation and R&D; Diffusion Processes; Open Innovation.
    JEL: O3 O30 O31 O32 O33 O34
    Date: 2022–06–11
  7. By: Zhaoqi Zang; Xiangdong Xu; Kai Qu; Ruiya Chen; Anthony Chen
    Abstract: The unavoidable travel time variability in transportation networks, resulted from the widespread supply side and demand side uncertainties, makes travel time reliability (TTR) be a common and core interest of all of the stakeholders in transportation systems, including planners, travelers, service providers, and managers. This common and core interest stimulates extensive studies on modeling TTR. Researchers have developed a range of theories and models of TTR, many of which have been incorporated into transportation models, transport policies, and project appraisals. Adopting the network perspective, this paper aims to provide an integrated framework for summarizing the methodological developments of modeling TTR in transportation networks, including its characterization, evaluation and valuation, and traffic assignment. Specifically, the TTR characterization provides a whole picture of travel time distribution in transportation networks. TTR evaluation and TTR valuation interpret abstract characterized TTR in a simple and intuitive way to be well understood by different stakeholders of transportation systems. Lastly TTR-based traffic assignment investigates the effects of TTR on the individual users travel behavior and consequently the collective network flow pattern. As the above three topics are mainly separately studied in different disciplines and research areas, the integrated framework allows us to better understand their relationships and may contribute to developing possible combinations of TTR modeling philosophy. Also, the network perspective enables to focus on common challenges of modeling TTR, especially the uncertainty propagation from the uncertainty sources to the TTR at spatial levels including link, route, and the entire network. Some potential directions for future research are discussed in the era of new data environment, applications, and emerging technologies.
    Date: 2022–06
  8. By: Andrea Fazio (University of Pavia, Pavia, Italy); Francesco Scervini (University of Pavia, Pavia, Italy); Tommaso Reggiani (Masaryk University, Brno, Czech Republic)
    Abstract: Social media play a relevant role in shaping social attitudes and economic behaviors of individuals. One of the first very well-known examples of social media campaign is the Ice Bucket Challenge (IBC), a charity campaign that went viral on social networks in August 2014 aiming at collecting money for the research on amyotrophic lateral sclerosis (ALS). We rely on UK longitudinal data to investigate the causal impact of the Ice Bucket Challenge on pro-social behaviors. In detail, this study shows that having been exposed to the IBC increases the probability of donating money, and it increases the amount of donating money among those who donate at most £100. We also find that exposure to the IBC has increased the probability of volunteering and the level of interpersonal trust. However, all these results, but the one on the intensive margins of donations, have a short duration, limited to less than one year, supporting the prevalent consensus that social media campaigns may have only short-term effects.
    Keywords: Donations, Volunteering, Altruism, Social media campaigns, Ice bucket challenge
    JEL: D64 O35
    Date: 2022–07
  9. By: Jolian McHardy (Department of Economics, University of Sheffield, UK)
    Abstract: We develop a network model of differentiated transport services explicitly incorporating interchangeable and rival aspects, characteristic of many transport systems, allowing exploration of the implications of strategic interaction on pricing amongst multiple rival operators within and across modes. The model offers a framework for studying the impacts of alternative policy scenarios with a wide variety of applications across the transport sector in a way that is tractable and allows meaningful analysis. We illustrate some of the uses of the framework through a series of applications which demonstrate the importance of explicitly recognising the dual rival and interchangeable aspects across multiple operators. Amongst other things, we show that the base model, which we characterise as n = 2, and which has been widely employed in the transport literature, in some respects represents a special case and that the relative size of equilibrium profit, consumer surplus and welfare across regimes as well as the rankings of different regimes across these performance indicators are non-monotonic in n, hence justifying a framework which explicitly allows n to vary. One application examines the performance of the multi-operator ticketing card scheme under guidelines operating in the UK local bus sector. This features as a key part in the UK government’s local bus transport strategy but is also due to expire in 2026 and is currently under statutory review. A calibration exercise shows this regime may offer higher profit, consumer surplus and welfare as well as a more extensive service provision than the ‘free-market’ case. However, under non-trivial fixed costs, it may not sustain as large a network as under the ‘free-market’, reversing the consumer surplus and welfare rankings.
    Keywords: Multi-operator; Transport Networks; Pricing; Welfare
    JEL: D43 L13 L92 R48
    Date: 2022–07
  10. By: Vincent Leon; S. Rasoul Etesami; Rakesh Nagi
    Abstract: We consider the diffusion of innovation in social networks using a game-theoretic approach. Each individual plays a coordination game with its neighbors and decides what alternative product to adopt to maximize its payoff. As products are used in conjunction with others and through repeated interactions, individuals are more interested in their long-term benefits and tend to show trustworthiness to others to maximize their long-term payoffs. To capture such trustworthy behavior, we deviate from the expected utility theory and use a new notion of rationality based on limited-trust equilibrium (LTE). By incorporating such notion into the diffusion model, we analyze the convergence of emerging dynamics to their equilibrium points using a mean-field approximation. We study the equilibrium state and the convergence rate of the diffusion process using the absorption probability and the expected absorption time of a reduced-size absorbing Markov chain. We also show that the LTE diffusion model under the best-response strategy can be converted to the well-known linear threshold model. Simulations show that when agents behave trustworthily, their long-term payoffs will increase significantly compared to the case when they are solely self-interested. Moreover, the Markov chain analysis provides a good estimation of the convergence property over random networks.
    Date: 2022–06
  11. By: César Ducruet; Hidekazu Itoh
    Abstract: This research investigates the determinants of ship turnaround times at about 2,300 container ports between 1977 and 2016, based on nearly 3 million daily vessel movements. It adopts a multilevel approach combining territorial and network indicators to characterize ports, and proposes a new methodology calculating shipping delays. Main results reveal that port connectivity, Gross Domestic Product per capita, the number of vessel calls, and island location foster efficient port operations. Conversely, urban population, voyage delays at sea, maximum ship size, and upstream location increase turnaround time. While average turnaround time and inter-port sailing time have both regularly declined, operational and technological changes in the ports and maritime sector - especially after the 2007/8 global financial crisis - accelerated intra-port time and slowed down inter-port time. This relational and spatial approach also underlines the geographic differentiation of ship times nationally and regionally, as it is far from being randomly distributed on the globe.
    Keywords: congestion; containerization; liner shipping networks; port cities; ship turnaround time; uncertainty
    JEL: L90 N70 R40
    Date: 2022
  12. By: Karamanis, Dimitris
    Abstract: This paper employs a panel vector autoregressive (PVAR) approach to investigate the relationship among military expenditure, investment, and economic growth, over the period after the enforcement of the Maastricht treaty (1994–2018) in 25 European countries that participate in the Permanent Structured Cooperation (PESCO). By using the Louvain community detection algorithm on the network links that have been established through defence partnerships in PESCO projects, two different country clusters emerge. Findings suggest that military expenditures can stimulate economic growth but the effects may not be common for all Member States, which might benefit from the involvement in joint defence projects to maximize the effectiveness of their defence spending.
    Keywords: defence partnerships; military expenditures; investments; economic growth; PVAR; PESCO
    JEL: H56 C33 O47
    Date: 2022–07
  13. By: Svetlana Klessova (GREDEG - Groupe de Recherche en Droit, Economie et Gestion - UNS - Université Nice Sophia Antipolis (1965 - 2019) - COMUE UCA - COMUE Université Côte d'Azur (2015-2019) - CNRS - Centre National de la Recherche Scientifique - UCA - Université Côte d'Azur); Sebastian Engell (TU - Technische Universität Dortmund [Dortmund]); Catherine Thomas (GREDEG - Groupe de Recherche en Droit, Economie et Gestion - UNS - Université Nice Sophia Antipolis (1965 - 2019) - COMUE UCA - COMUE Université Côte d'Azur (2015-2019) - CNRS - Centre National de la Recherche Scientifique - UCA - Université Côte d'Azur)
    Abstract: Publicly funded multi-actor research, development and innovation projects are a setting where a network of multiple organizational actors form a temporary consortium to jointly create new knowledge and marketupstream innovations. The couplings between the organizational actors and subgroups of these actors represent joint work that leads to flows of knowledge and flows of activities. The dynamics of the couplings in this empirical context and their implications are not well understood yet. Using an inductive comparative multiple case study of projects funded in European Research and Innovation Programmes, we investigated 4 projects with 54 organizational actors, which produced 50 innovations. The evolutions of all couplings went through the same phases, although the temporality of the phases differed. We identified eight types of evolutions of couplings and their underlying generative mechanisms. These evolutions led to different, mostly negative implications on the planned collaborative innovations. Particularly, we observed a systematic degradation of the couplings that were planned to connect subgroups of organizational actors. Over time, the projects became less collaborative than planned, and they have a tendency to fragment into isolated activities by subgroups of actors. Based on these findings, we propose an emerging process model which helps to better understand how and why the couplings evolve in multi-actor RDI projects.
    Keywords: Multi-actor projects,Research,Development,Collaborative innovation,Process,Evolution,Tie,Module,Interface,Output,Qualitative research,Coupling,Interdependency,Collaboration
    Date: 2022

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