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on Network Economics |
| By: | Pollock, R. |
| Abstract: | (In)direct network effects arise frequently in economic models but, for reasons of analytical tractability, are often assumed to be linear. Here, we examine the general non-linear case with two platforms. We establish the conditions characterising equilibria and show that welfare changes can be related in a simple, intuitive way to the degree of diminishing returns of the network effects function. |
| Keywords: | Network Effects; Indirect Network Effects; Platforms; Welfare |
| JEL: | L13 |
| Date: | 2009–04–07 |
| URL: | http://d.repec.org/n?u=RePEc:cam:camdae:0915&r=net |
| By: | Coralio Ballester (Universidad de Alicante); Antoni Calvó-Armengol (ICREA,Universitat Autònoma de Barcelona); Yves Zenou (Stockholm University, Research Institute of Industrial Economics (IFN) and CREAM) |
| Abstract: | Delinquents are embedded in a network of relationships. Social ties among delinquents are modeled by means of a graph where delinquents compete for a booty and benefit from local interactions with their neighbors. Each delinquent decides in a non-cooperative way how much delinquency effort he will exert. Using the network model developed by Ballester et al. (2006), we characterize the Nash equilibrium and derive an optimal enforcement policy, called the key-player policy, which targets the delinquent who, once removed, leads to the highest aggregate delinquency reduction. We then extend our characterization of optimal single player network removal for delinquency reduction, the key player, to optimal group removal, the key group. We also characterize and derive a policy that targets links rather than players. Finally, we endogenize the network connecting delinquents by allowing players to join the labor market instead of committing delinquent offenses. The key-player policy turns out to be much more complex since it depends on wages and on the structure of the network. |
| Date: | 2008–04 |
| URL: | http://d.repec.org/n?u=RePEc:crm:wpaper:200912&r=net |
| By: | Beegle, Kathleen; Filmer, Deon; Stokes, Andrew; Tiererova, Lucia |
| Abstract: | Increasing adult mortality due to HIV/AIDS in Sub-Saharan Africa raises considerable concerns about the welfare of surviving children. Studies have found substantial variability across countries in the negative impacts of orphanhood on child health and education. One hypothesis for this variability is the resilience of the extended family network in some countries to care for orphans-networks under increasing pressure by the sheer number of orphans in many settings. Using household survey data from 21 countries in Africa, this study examines trends in orphanhood and living arrangements, and the links between the two. The findings confirm that orphanhood is increasing, although not all countries are experiencing rapid rises. In many countries, there has been a shift toward grandparents taking on increased childcare responsibility-especially where orphan rates are growing rapidly. This suggests some merit to the claim that the extended network is narrowing, focusing on grandparents who are older and may be less able to financially support orphans than working-age adults. However there are also changes in childcare patterns in countries with stable orphan rates or low HIV prevalence. This suggests future work on living arrangements should not exclude low HIV/AIDS prevalence countries, and explanations for changes should include a broader set of factors. |
| Keywords: | Street Children,HIV AIDS,Youth and Governance,Primary Education,Population Policies |
| Date: | 2009–03–01 |
| URL: | http://d.repec.org/n?u=RePEc:wbk:wbrwps:4889&r=net |