119 research outputs found
Contagion and state dependent mutations
Full text linkEarly results of evolutionary game theory showed that the risk dominant equilibrium is uniquely selected on the long run by the best response dynamics with mutation. Bergin and Lipman (1996) qualified this result by showing that for a given population size the evolutionary process can select any strict Nash equilibrium if the probability of choosing a nonbest reply is state-dependent. This paper shows that the unique selection of the risk dominant equilibrium is robust with respect to state dependent mutation in local interaction games. More precisely, for a given mutation structure there exists a minimum population size beyond which the risk dominant equilibrium is uniquely selected. Our result is driven by contagion and cohesion among players, which exists only in local interaction settings and favors the play of the risk dominant strategy. Our result strengthens the equilibrium selection result of evolutionary game theor
Independence and heterogeneity in games of incomplete information
No full textThis paper provides a sufficient condition for existence and uniqueness of equilibrium, which is in monotone pure strategies, in games of incomplete information. First, we show that if each player’s incremental ex post payoff is uniformly increasing in its own action and type, and its type is sufficiently uninformative of the types of its opponents (independence), then its expected payoff satisfies a strict single crossing property in its own action and type, for any strategy profile played by its opponents. This ensures that a player’s best response to any strategy profile is a monotone pure strategy. Secondly, we show that if, in addition, there is sufficient heterogeneity of the conditional density of types, then the best response correspondence is a contraction mapping. This ensures equilibrium existence and uniqueness. In contrast to existing results, our uniqueness result does not rely on strategic complementarities; this allows for a wider range of applications
Contagion and state dependent mutations
No full textEarly results of evolutionary game theory showed that the risk dominant equilibrium is uniquely selected in the long run under the best-response dynamics with mutation. Bergin and Lipman (1996) qualified this result by showing that for a given population size, the evolutionary process can select any strict Nash equilibrium if the probability of choosing a nonbest response is state-dependent. This paper shows that the unique selection of the risk dominant equilibrium is robust with respect to state dependent mutation in local interaction games. More precisely, for any given mutation structure there exists a minimum population size beyond which the risk dominant equilibrium is uniquely selected. Our result is driven by contagion and cohesion among players, which exist only in local interaction settings and favor the risk dominant strategy. Our result strengthens the equilibrium selection result of evolutionary game theory
Which sectors make the poor countries so unproductive?
Full text linkStandard growth accounting exercises find large cross-country differences in aggregate TFP. Here we ask whether specific sectors are driving these differences, and, if this is the case, which these problem sectors are. We argue that to answer these questions we need to consider four sectors. In contrast, the literature typically considers only two sectors. Our four sectors produce services (nontradable consumption), consumption goods (tradable consumption), construction (nontradable investment), and machinery and equipment (tradable investment). Interacting the data from the 1996 benchmark study of the Penn World Tables with economic theory, we find that the TFP differences across countries are much larger in the two tradable sectors than in the two nontradable sectors. This is consistent with the Balassa--Samuelson hypothesis. We also find that within the tradable sectors the TFP differences are much larger in machinery and equipment than in consumption goods. We illustrate the usefulness of our findings by accounting for the conflicting results of the existing two--sector analyses and by developing criteria for a successful theory of aggregate TFP
The long-lived effects of historic climate on the wealth of nations
Full text linkWe investigate the long-run consequences of historic, climatic temperatures (1730-2000) for the modern cross-country income distribution. Using a newly constructed dataset of climatic temperatures stretching over three centuries (18th, 19th, and 20th), we estimate a robust and significant time-varying, nonmonotonic effect of climatic temperature upon current incomes for a crosssection of 167 countries. We find a large, positive effect of 18th century climatic temperature and an even larger, negative effect of 19th century climatic temperature upon current incomes. When historic, climatic temperature is introduced, the effect of 20th century climatic temperature on current income is either weakly positive or insignificant. Our findings are robust to various sub-samples, additional geographic controls, and alternative income measures. The negative relationship between current, climatic temperature and current income that is commonly estimated appears to reflect the long-run effect of climatic variations in the 18th and 19th centurie
Noisy contagion without mutation
No full textIn a local interaction game agents play an identical stage game against their neighbours over time. For nearest neighbour interaction, it is established that, starting from a random initial configuration in which each agent has a positive probability of playing the risk dominant strategy, a sufficiently large population coordinates in the long-run on the risk dominant equilibrium almost surely. Our result improves on Blume (1995), Ellison (2000), and Morris (2000) by showing that the risk dominant equilibrium spreads to the entire population in a two dimensional lattice and without the help of mutation, as long as there is some randomness in the initial configuratio
Independence, Heterogeneity and Uniqueness in Interaction Games
Get PDFThis paper shows that incomplete information and sufficient heterogeneity of players can ensure uniqueness in interaction games. In contrast to recent work on uniqueness in interaction games, we do not require strategic complementarity. There are two parts to the argument. First, if a player’s signal is sufficiently uninformative of the signals of its opponents (in the sense of the Fisher information of the signal), then the player’s best response to any strategy profile of its opponents is non-decreasing in its signal. Secondly, a contraction mapping argument shows that sufficient heterogeneity ensures that equilibrium is unique.Co-ordination, Interaction games, Heterogeneity, Unique equilibrium
Neoclassical Growth Model with Externalities
Get PDFThis paper explores the local stability properties of the steady state in the twosector neoclassical growth model with sector–specific externalities. We show analytically that capital adjustment costs of any size preclude local indeterminacy nearby the steady state for every empirically plausible specification of the model parameters. More specifically, we show that when capital adjustment costs of any size are considered, a necessary condition for local indeterminacy is an upward-sloping labor demand curve in the capital-producing sector, which in turn requires an implausibly strong externality. We show numerically that capital adjustment costs of plausible size imply determinacy nearby the steady state for empirically plausible specifications of the other model parameters. These findings contrast sharply with the previous finding that local indeterminacy occurs in the two-sector model for a wide range of plausible parameter values when capital adjustment costs are abstracted from.capital adjustment costs; determinacy; externality; local indeterminacy; stability.
Contagion and state dependent mutations
Full text linkEarly results of evolutionary game theory showed that the risk dominant equilibrium is uniquely selected on the long run by the best response dynamics with mutation. Bergin and Lipman (1996) qualified this result by showing that for a given population size the evolutionary process can select any strict Nash equilibrium if the probability of choosing a nonbest reply is state-dependent. This paper shows that the unique selection of the risk dominant equilibrium is robust with respect to state dependent mutation in local interaction games. More precisely, for a given mutation structure there exists a minimum population size beyond which the risk dominant equilibrium is uniquely selected. Our result is driven by contagion and cohesion among players, which exists only in local interaction settings and favors the play of the risk dominant strategy. Our result strengthens the equilibrium selection result of evolutionary game theory
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