Daniel C. Opolot
Senior Lecturer, Department of Economics, University of Pretoria
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Hello & welcome to my page. I am a Senior Lecturer at the Economics Department of the University of Pretoria. My research interests are in game theory, social and economic networks, applied microeconomics, and development economics.
I hold a doctoral degree in microeconomics from Maastricht University, and I was a post-doctoral research fellow at the African Institute of Financial Markets and Risk Management (AIFMRM), University of Cape Town.
Research
Strategic diffusion in networks through contagion (with Théophile T. Azomahou)
This paper studies the diffusion of products and behaviour with coordination effects through social networks when agents are myopic best responders. We develop a new network measure, the contagion threshold, that determines when a p-dominant action—an action that is a best response when adopted by at least proportion p of an agent’s opponents—spreads to the whole population starting from a group of players whose size is smaller than half and independent of the population size. We show that a p-dominant action spreads to the whole network whenever the contagion threshold of that network is greater or equal to p. We then show that in settings where agents regularly or occasionally experiment and choose non-optimal actions, there exists a threshold level of experimentation below which a p-dominant action is chosen with the highest probability in the long run. This result implies that targeted contagion, a network-wide diffusion of actions initiated by targeting agents, is justified even in settings where agents’ decisions are noisy.
Journal of Evolutionary Economics
On the relationship between p-dominance and stochastic stability in network games
This paper examines the properties of networks that determine the uniqueness of long-run equilibria emerging from symmetric coordination games when players are myopic best responders. We identify the contagion threshold and the network diameter as two measures of finite networks that determine when strategies in the minimal p-best response set of a coordination game are uniquely stochastically stable. We show that when the contagion threshold is greater or equal to p, strategies in the minimal p-best response set are uniquely stochastically stable in strongly connected networks with diameter greater or equal to seven. The contagion threshold and the network diameter are easy to compute and their values are unique for every strongly connected network.
International Journal of Game Theory
Discussants
We study the role of informal collaboration in academic knowledge production using published research papers previously presented and discussed at the NBER Summer Institute. We show that papers that have a discussant are published in highly-ranked journals and are more likely to be published in a top journal. Conditional on having a discussant, the quality of a paper’s journal outlet increases in the discussant’s prolificness and editorial experience. This supports the idea that discussants help reduce information asymmetries that are inherent in the academic publication process. Conversely, using social network analysis we find no evidence that citations accumulate because discussants diffuse information about the paper.
Working papers
Contagion, network cohesion and long run stability in evolutionary games
This paper studies how the network structure affects the long-run equilibria emerging in coordination games when agents are myopic best responders. Our analysis builds-on the properties of the process of contagion. We demonstrate that when contagion is feasible, the network diameter, a measure of the cohesiveness of the network, determines the uniqueness of long-run equilibria. The maximum group cohesion is one of the network measures that determines the feasibility of contagion. We show that for regular cyclic networks, there exists a threshold network diameter above which strategies in the smallest iterated p-best response set, for p equal to the maximum group cohesion, are uniquely stochastically stable. We discuss how these results can be extended to evolutionary dynamics on arbitrary networks using different network measures that determine the feasibility of contagion.
Costly word-of-mouth learning in networks (with Théophile T. Azomahou)
This paper develops a framework for word-of-mouth learning in networks where agents strategically decide when to take an irreversible action. Agents face a trade-off between taking an irreversible action early enough to avoid the cost of waiting and waiting to receive more information to increase confidence in their choice. We characterize equilibrium exit times and establish conditions for correct learning in large societies. The necessary conditions for correct learning are: (i) no single or small group of agents should have unbounded influence as measured by conditional in-degree; (ii) The underlying network must have a bounded diameter. Finally, we show that the presence of noise in signals prolongs exit times, and hence increases the likelihood of asymptotic learning.
How central agents affect group behaviour and the speed of learning
Centralized network structures, which consist of at least one actor – a central agent – whose behaviour is observed by the rest of the group are predominant across social, political and economic settings. In public and corporate sectors, central agents such as managers and CEOs, shape organizational culture and identity, which in turn affects organizational performance. This paper studies how central agents affect behaviour formation through social learning. We show that although central agents play a crucial role in driving the group to a consensus, they do not necessarily exert the most influence on the group’s equilibrium behaviour. In equilibrium, an agent’s influence corresponds to her eigenvector centrality. We also examine the convergence rate of behaviour formation and show that it depends on the degree to which central agents facilitate group cohesion.
Prejudice, group cohesion and the dynamics of disagreement
This paper studies how individual prejudice – a set of preconceived and inflexible opinions – and group cohesion generate everlasting public disagreement in models of learning by averaging. We consider an endogenous model of opinion formation where agents compromise between respecting their own personal prejudice and conforming to the opinions held by others with whom they share close ties. We quantify the extent of equilibrium disagreement and show that its magnitude increases with the intensities of prejudice and group cohesion. Similarly, the speed of learning is a logarithmic function of the intensities of prejudice and group cohesion.
Informal Intellectual Collaboration with Central Colleagues (with Co-Pierre Georg and Michael E. Rose)
When preparing a research article, academics engage in informal intellectual collaboration by asking their colleagues for feedback. This collaboration gives rise to a social network between academics. We study whether informal intellectual collaboration with an academic who is more central in this social network results in a research article having higher scientific impact. To address the well-known reflection problem in estimating network effects, we use the assignment of discussants at NBER summer institutes as a quasi-natural experiment. We show that manuscripts discussed by a discussant with a 10% higher than average Bonacich centrality rank results in 1.4% more citations and a 5% higher probability that an article is published in a top journal. To illustrate our results, we develop a structural model in which a positive externality from intellectual collaboration implies that collaborating with a more central colleague results in larger scientific impact of the research article. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2877586
Ongoing projects
The Rate of Scientific Progress and the Structure of the Scientific Community (with Michael E. Rose)
Energy access and SMEs performance: Evidence from West-Nile, Uganda
Contact
Email: daniel.opolot@up.ac.za, University of Pretoria, Department of Economics, Hatfield 0083, South Africa