Strategic Experimentation with Exponential Bandits

This paper studies a game of strategic experimentation with two-armed bandits whose risky arm might yield a payoff only after some exponentially distributed random time. Because of free-riding, there is an inefficiently low level of experimentation in any equilibrium where the players use stationary Markovian strategies with posterior beliefs as the state variable. After characterizing the unique symmetric Markovian equilibrium of the game, which is in mixed strategies, we construct a variety of pure-strategy equilibria. There is no equilibrium where all players use simple cut-off strategies. Equilibria where players switch finitely often between the roles of experimenter and free-rider all lead to the same pattern of information acquisition; the efficiency of these equilibria depends on the way players share the burden of experimentation among them. In equilibria where players switch roles infinitely often, they can acquire an approximately efficient amount of information, but the rate at which it is acquired still remains inefficient; moreover, the expected payoff of an experimenter exhibits the novel feature that it rises as players become more pessimistic. Finally, over the range of beliefs where players use both arms a positive fraction of the time, the symmetric equilibrium is dominated by any asymmetric one in terms of aggregate payoffs

Towards an Analytical Framework for Assessing Property Rights to Natural Resources: A Case Study in the Communal Areas of Zimbabwe

A taxonomy for describing property rights to natural resources is described and applied in a Zimbabwean case study. The taxonomy allows: tenures to be systematically compared and contrasted; incentives for natural resource management to be identified; and the evolution of tenure to natural resources to be assessed. In the case study, we find: key differences between tenure types, all termed "communal"; a wide range of tenure arrangements that transcend concepts of "tree" and "land tenure"; information suggesting that the promotion of tree planting may work on some tenure types, but is likely to fail on others; and that the evolution of indigenous tenure to natural resources seems to have been somewhat immune from external changes in institutional systems. Prospects for further theoretical and empirical advances are discussed within the context of the property rights framework presented.incentives, natural resources, property rights framework/taxonomy, tenure, Zimbabwe, Resource /Energy Economics and Policy,

Strategic Experimentation: The Case of the Poisson Bandits

This paper studies a game of strategic experimentation in which the players learn from the experiments of others as well as their own. We first establish the efficient benchmark where the players co-ordinate in order to maximise joint expected payoffs, and then show that, because of free-riding, the strategic problem leads to inefficiently low levels of experimentation in any equilibrium when the players use stationary Markovian strategies. Efficiency can be approximately retrieved provided that the players adopt strategies which slow down the rate at which information is acquired; this is achieved by their taking periodic breaks from experimenting, which get progressively longer. In the public information case (actions and experimental outcomes are both observable), we exhibit a class of non-stationary equilibria in which the $\varepsilon$-efficient amount of experimentation is performed, but only in infinite time. In the private information case (only actions are observable, not outcomes), the breaks have two additional effects: not only do they enable the players to finesse the inference problem, but also they serve to signal their experimental outcome to the other player. We describe an equilibrium with similar non-stationary strategies in which the $\varepsilon$-efficient amount of experimentation is again performed in infinite time, but with a faster rate of information acquisition. The equilibrium rate of information acquisition is slower in the former case because the short-run temptation to free-ride on information acquisition is greater when information is public.

Strategic Experimentation with Exponential Bandits

This paper studies a game of strategic experimentation with two-armed bandits whose risky arm might yield a payoff only after some exponentially distributed random time. Because of free-riding, there is an inefficiently low level of experimentation in any equilibrium where the players use stationary Markovian strategies with posterior beliefs as the state variable. After characterizing the unique symmetric Markovian equilibrium of the game, which is in mixed strategies, we construct a variety of pure-strategy equilibria. There is no equilibrium where all players use simple cut-off strategies. Equilibria where players switch finitely often between the roles of experimenter and free-rider all lead to the same pattern of information acquisition; the efficiency of these equilibria depends on the way players share the burden of experimentation among them. In equilibria where players switch roles infinitely often, they can acquire an approximately efficient amount of information, but the rate at which it is acquired still remains inefficient; moreover, the expected payoff of an experimenter exhibits the novel feature that it rises as players become more pessimistic. Finally, over the range of beliefs where players use both arms a positive fraction of the time, the symmetric equilibrium is dominated by any asymmetric one in terms of aggregate payoffs.Strategic Experimentation ; Two-Armed Bandit ; Exponential Distribution ; Bayesian Learning ; Markov Perfect Equilibrium ; Public Goods

Unravelling an Extra Neutral Gauge Boson at the LHC using Third Generation Fermions

We study the potential to use measurements of extra neutral gauge bosons (Z') properties in pp collisions at the Large Hadron Collider to unravel the underlying physics. We focus on the usefulness of third generation final states (tau, b, t) in distinguishing between models with non-universal Z'-fermion couplings. We present an update of discovery limits of Z's including the 2010-2011 LHC run and include models with non-universal couplings. We show how ratios of sigma(pp -> Z' -> ttbar), sigma(pp -> Z' -> bbbar), and sigma(pp -> Z' -> tau^+tau^-) to sigma(pp -> Z' -> mu^+mu^-) can be used to distinguish between models and measure parameters of the models. Of specific interest are models with preferential couplings, such as models with generation dependent couplings. We also find that forward-backward asymmetry measurements with third generation fermions in the final state could provide important input to understanding the nature of the Z'. Understanding detector resolution and efficiencies will be crucial for extracting results

Beyond the brain drain: Redefining the professions

The traditional policy measures employed by Third World governments to reduce the “brain drain”, the migration of critical groups of professionals to industrialised countries, have proved to be largely ineffective. The following article suggests a redefinition of job content and of professional training in the interests of greater relevance to national needs and resources. This, the author argues, would incidentally remove the possibility of brain drain which was always a mere symptom of the real problem

Using Final State Pseudorapidities to Improve s-channel Resonance Observables at the LHC

We study the use of final state particle pseudorapidity for measurements of s-channel resonances at the LHC. Distinguishing the spin of an s-channel resonance can, in principle, be accomplished using angular distributions in the centre-of-mass frame, possibly using a centre-edge asymmetry measurement, A_CE. In addition, forward-backward asymmetry measurements, A_FB, can be used to distinguish between models of extra neutral gauge bosons. In this note we show how these measurements can be improved by using simple methods based on the pseudorapidity of the final state particles and present the expected results for A_FB and A_CE for several representative models.Comment: 6 pages, 4 figures, 1 table; typos fixed, improved visibility of figures for greyscale printin