Evolution of harvesting strategies: replicator and resource dynamics

Abstract. Economic theories of managing renewable resources, such as fisheries and forestry, traditionally assume that individual harvesters are perfectly rational and thus able to compute the harvesting strategy that maximizes their discounted profits. The current paper presents an alternative approach based on bounded rationality and evolutionary mechanisms. It is assumed that individual harvesters face a choice between two harvesting strategies. The evolution of the distribution of strategies in the population is modeled through a replicator dynamics equation. The latter captures the idea that strategies yielding above average profits are demanded more than strategies yielding below average profits, so that the first type ends up accounting for a larger part in the population. From a mathematical perspective, the combination of resource and evolutionary processes leads to complex dynamics. The paper presents the existence and stability conditions for each steady-state of the system and analyzes dynamic paths to the equilibrium. In addition, effects of changes in prices are analyzed. A main result of the paper is that under certain conditions both strategies can survive in the long-run. Correspondence to: J. Noailly     

Rustem,B., and Howe,M.: Algorithms for Worst-case Design and Applications to Risk Management. XV, 389 pp. Princeton University Press,Princeton, New Jersey. 2002. Hardcover £ 52.00.

Journal of Economics -     

Evaluating Projects and Assessing Sustainable Development in Imperfect Economies

We are interested in three related questions:(1) How should accounting prices be estimated?(2) How should we evaluate policy change in animperfect economy? (3) How can we check whetherintergenerational well-being will be sustainedalong a projected economic programme? We do notpresume that the economy is convex, nor do weassume that the government optimizes on behalfof its citizens. We show that the same set ofaccounting prices should be used both forpolicy evaluation and for assessing whether ornot intergenerational welfare along a giveneconomic path will be sustained. We also showthat a comprehensive measure of wealth,computed in terms of the accounting prices, canbe used as an index for problems (2) and (3)above. The remainder of the paper is concernedwith rules for estimating the accounting pricesof several specific environmental naturalresources, transacted in a few well knowneconomic institutions.     

Playing safe in coordination games:: the roles of risk dominance, payoff dominance, and history of play

This paper presents results from a series of experiments designed to test the impact on subject behavior of changes in the risk dominance and payoff dominance characteristics of two player coordination games. The main finding is that changes in risk dominance significantly affect play of the subjects, whereas changes in the level of payoff dominance do not. Observed history of play also has an important influence on subject behavior, both when subjects are randomly rematched after each game and when they remain matched with the same individual for a sequence of games.     

A modified logit model for time series with an application to the pricing behaviour of manufacturing firms in Australia

The modified logit model (Amemiya and Nold, 1975) is generalised to the case where the error term is autocorrelated. The asymptotic distribution (as n →∞ and T →∞) of a feasible GLS estimator of β is derived. Tests of linear restrictions on β and the significance of ρ are presented. The results of the applied work suggest that the factors which explain the pricing behaviour of manufacturing firms, as reported in the tendency survey conducted by the Australian Chamber of Commerce and Industry and the Westpac Banking Corporation, include historical inflation rates of up to 7 quarters and capacity utilisation. First version received: March 2001/Final version received: July 2002 RID="*" ID="*"  The first draft of this paper was written while the author was on study leave at the Department of Econometrics, University of Sydney, Australia.     

General training by firms, apprentice contracts, and public policy

Workers will not pay for general on-the-job training if contracts are not enforceable. Firms may if there are mobility frictions. Private information about worker productivities, however, prevents workers who quit receiving their marginal products elsewhere. Their new employers then receive external benefits from their training. In this paper, training firms increase profits by offering apprenticeships which commit firms to high wages for those trainees retained on completion. At these high wages, only good workers are retained. This signals their productivity and reduces the external benefits if they subsequently quit. Regulation of apprenticeship length (a historically important feature) enhances efficiency. Appropriate subsidies enhance it further.     

An equilibrium analysis of information aggregation and fluctuations in markets with discrete decisions

This paper shows how the interaction between decentralized information gathering and discreteness of investment decisions at the individual level can generate random fluctuations in aggregate investment that involve occasionally large allocation errors. This interaction is illustrated in a model in which private information is costly to acquire and prices reveal information. The unique rational expectations equilibrium outcome of the model is shown to always be noisy and characterized by investment levels which may be high simply because uninformed investors are buying under the impression that the high price is a signal of good investment opportunities.     

Taxation and household portfolio composition: US evidence from the 1980s and 1990s

This paper explores the relationship between household marginal income tax rates, the set of financial assets that households own, and the portfolio shares accounted for by each of these assets. It analyzes data from the 1983, 1989, 1992, 1995, and 1998 Surveys of Consumer Finances and develops a new algorithm for imputing federal marginal tax rates to households in these surveys. The empirical findings suggest that marginal tax rates have important effects on asset allocation decisions. The probability that a household owns tax-advantaged assets, such as tax-exempt bonds or assets held in tax-deferred accounts, is positively related to its tax rate on ordinary income. In addition, the portfolio share invested in corporate stock, which is taxed less heavily than interest bearing assets, is increasing in the household’s ordinary income tax rate. Holdings of heavily taxed assets, such as interest-bearing accounts, decline as a share of wealth as a household’s marginal tax rate increases.     

The good,the bad and the ugly: agent behavior and efficiency in open and closed organizations

Current literature has largely ignored the fact that some organizations are highly selective when admitting new agents while others are more open. In addition, some organizations audit or sort agent behavior within the organization more aggressively than others. One might expect a priori that closed, highly selective, organizations would always be more efficient because they screen out the worst types, which could lead to better agent behavior. We show that this is not the case. Specifically, when agent behavior in equilibrium is uniform across organizations (i.e., when the number of agents behaving the same way is identical), closed organizations are inefficient. However, when agent behavior varies across organizations, closed organizations may or may not be inefficient, depending on net payoffs to the organization and the agents. Our analysis implies that organizations should choose the open type when screening or sorting costs are high, when there is a high frequency of good agent types in the population, when agent misbehavior does not reduce output significantly, and when penalties for misbehavior are large. The paper has benefitted from useful comments by David Flath, Charles Knoeber, Claudio Mezzetti, two anonymous referees and participants of the Spring 2005 Midwest Economic Theory meetings at Vanderbilt University, the 2005 meetings of the Society for the Advancement of Economic Theory in Vigo, Spain, the 2005 conference on Research in Economic Theory and Econometrics in Syros, Greece, and workshops at North Carolina State University, Texas A&M University and McGill University.     

Critical factors in computing externalities for electricity resources

The New York State Environmental Externalities Cost Study and computerized externality model (EXMOD) are used to examine the specification of methods design and application factors in the computation of electricity externalities. We report the sensitivity of externality estimates with alternative specifications for 15 different factors in the analysis, including the selection of facility type, site, and operating characteristics; air emission assumptions and air modeling procedures; dose-response assumptions; economic valuation assumptions; and other modeling procedures and assumptions. Many of the factors that most influence externality computations can be well specified in the analysis, such as the facility type, age, characteristics, emission rates, whether there is SO₂ trading, and the inclusion of long range impacts. Most significant among the factors for which there remains significant scientific uncertainty are the selection and application of air dispersion models, selection of air pollution thresholds for health impacts, reduced life span risks associated with ozone exposure and with long-term exposure to PM₁₀, values for CO₂ damages, and the value to be applied to increased risks of reduced life span for individuals age 65 or older.