On the solution of a stochastic optimal growth model

This note discusses a stochastic optimal growth model in which the optimal paths can be obtained by a simple direct argument. The structural characteristics of the model are the infinite horizon, the form of the instantaneous utility function, and uncertainty as a Wiener process in a linear production constraint. The note explains that, for optimality, at each point in time a formally identical problem must be solved. This implies that the optimal saving ratio must be constant.A proof, employing the rules of stochastic calculus, that the ensuing paths are the unique globally optimal paths is also given.We are very grateful to two referees of this journal for their invaluable comments and suggestions.     

Fixed price equilibria in an overlapping generations model with investment

We study fixed price temporary equilibria (with rationing) and sequences of temporary equilibria in a three commodities (goods, labor, bonds) overlapping generations model with endogenous investment. Young consumers, living two periods, work, consume, and buy bonds for financing next period's consumption. New firms, existing for two periods, make a production plan for the next period, taking into account expected rationing, assumed similar to present rationing. The plan determines the amount of goods to buy as capital, financed by bonds. Old firms produce, using labor and the previously bought capital. Different regimes exist and expectations can be self-fulfilling and self-destroying.We are grateful to the referees for helpful comments.     

A game theoretical approach to the international debt overhang

We consider an international financial problem called debt overhang, by which we mean a situation where a sovereign country has borrowed money from foreign banks and has been unable to fulfill the scheduled repayments for some period. The problem is formulated as a noncooperative game withn lender banks as players where each decides either to sell its loan exposure to the debtor country at the present price of debt on the secondary market, or to wait and keep its exposure. This game has many pure and mixed strategy Nash equilibria. We show, however, that in any Nash equilibrium, the resulting secondary market price remains almost the same as the present price for a large number of banks. We also obtain the comparative statics result that in a mixed strategy equilibrium, a bank with a smaller loan exposure has a greater tendency to sell than one with a larger loan exposure. We discuss the implications of these results for the functioning of the secondary market and the resolution of debt overhang.We thank J. Crémer, H. Haller, S. Mendes, and the referees of this Journal for helpful comments on earlier drafts.     

On some noncentral distribution problems for the mixture of two normal populations

Summary The null density of the multiple correlation coefficient when sampling from a mixture of two normal populations has been derived by Srivastava (1983). However, he does not express this density in a rather standard form. The present paper obtains the nonnull densities of the multiple correlation coefficient and the partial correlation coefficient in a rather standard form when sampling from a mixture of two normal populations.     

Efficiency wages and income taxes

The paper was written during a visit at the Ludwig-Maximilian-University of Munich in the summer of 1988. The hospitality of this institution, as well as the financial support from a Ruhrgas Scholarship under the West German Norwegian Scholarship Scheme, is gratefully acknowledged. Participants at various seminars have given useful comments and criticism. I am also grateful to two anonymous referees for their comments to an earlier version of the paper.     

A Delphi technology forecasting approach using a semi-Markov concept

This paper suggests a technology forecasting approach based on a semi-Markov model, which appropriately describes the probabilistic nature of a sequential technology development process. This approach focuses primarily on the utilization of the information that has been skipped in conventional Delphi survey data. That is, through a simple statistic, the interrelationships among sequential technology developments can be extracted in a formal structure of a semi-Markov model from the original Delphi panel's estimates. A simulation technique is developed to forecast the development process by utilizing the information on such interrelationships. This technique provides a flexible and useful tool for R&D planners or project managers, especially in postanalysis of Delphi forecasting. To make good use of the approach, a computer-based interactive Delphi data analysis system (IDEAS) is implemented in IBM PC.