Return migration, human capital accumulation and the brain drain

In this paper we present a model that explains migrations as decisions that respond to where human capital can be acquired more efficiently, and where the return to human capital is highest. The basic framework is a dynamic Roy model in which a worker possesses two distinct skills that can be augmented by learning by doing. There are different implicit prices, in different countries and different rates of skill accumulation. Our analysis contributes to the literature on the selection of immigrants and return migrants by offering a richer framework that may help to accommodate selection of emigrants and return migrants that are not immediately compatible with the one-dimensional skill model. Our analysis also has implications for the debate on brain drain and brain gain. In the two skills model presented here, return migration can lead to a mitigation of the brain drain, or even the creation of a “brain gain”, where those who return bring the home country augmented local skills.     

Dynamic Influences on Individual Choice Behavior

Research examining the process of individual decision making over time isbriefly reviewed. We focus on two major areas of work in choice dynamics:research that has examined how current choices are influenced by the historyof previous choices, and newer work examining how choices may be made toexploit expectations about options available in the future. A central themeof the survey is that if a general understanding of choice dynamics is toemerge, it will come through the development of boundedly-rational models ofdynamic problem solving that lie on the interface between economics andpsychology.     

Risk-aversely efficient random variables: Characterization and an application to growth under uncertainty

Consider a problem of choice from a set R of multivariate random variables. Let us examine only efficient elements of R which are optimal choices of risk averse decision-makers (whose aim is to maximize expected utility over R). We obtain a price characteristic of all risk-aversely efficient random variables in R. This result has been applied to multi-sector optimal growth model to obtain a characterization by competitive prices of all risk-aversely efficient stationary consumption programs.     

Hedging exchange rate risk: The multiperiod case

We analyse production and hedging in a multiperiod framework for a risk-averse exporting firm facing a random exchange rate. We extend the separation theorem to this multiperiod model. Our study shows that unbiased currency forward markets in all periods do not imply standard full hedging. Under some conditions, the firm tends to overhedge compared to the one-period hedging models.     

Stochastic growth with short-run prediction of shocks

We study a variation of the one-sector stochastic optimal growth model with independent and identically distributed shocks where agents acquire information that enables them to accurately predict the next period??s productivity shock (but not shocks in later periods). Optimal policy depends on the forthcoming shock. A ??better?? predicted realization of the shock that increases both marginal and total product always increases next period??s optimal output. We derive conditions on the degree of relative risk aversion and the elasticity of marginal product under which optimal investment increases or decreases with a better shock. Under fairly regular restrictions, optimal outputs converge in distribution to a unique invariant distribution whose support is bounded away from zero. We derive explicit solutions to the optimal policy for three well-known families of production and utility functions and use these to show that volatility of output, sensitivity of output to shocks, and expected total investment may be higher or lower than in the standard model where no new information is acquired over time; the limiting steady state may also differ significantly from that in the standard model.     

On optimal growth under uncertainty

In a recent paper Brock and Mirman showed that in a one-sector model of economic growth under uncertainty the long-run behavior of the optimal capital stock is governed by the basic properties of an acyclic ergodic Markov process. This paper considers a similar model and has two purposes. First, necessary and sufficient conditions for optimal policy functions are derived in a regime in which future utilities are discounted. These conditions lead, in an example, to an explicit optimal policy function, which is used to display the steady-state solution for the capital stock under an optimal policy. Secondly, in the Brock and Mirman paper it was assumed that the production functions are ordered. We show that all the properties proved by Brock and Mirman are satisfied even when the production functions are not ordered.     

On the behavioral differences between professional and amateur investors after the weekend

This paper compares the trading patterns of amateur and professional investors during the days following the weekend. The comparison is based on all the daily transactions of a large sample of both amateurs and professionally managed investors in a major brokerage house in Israel from 1994 to 1998. We find that weekends influence both amateurs and professional investors; however they affect them in opposite directions. Individuals increase both their buy and sell activities, and their propensity to sell rises more than their propensity to buy. Professionals on the other hand tend to perform fewer buy as well as sell trades after the weekend, but unlike individuals, the drop in their activity is almost the same for buy trades and for sell trades.