An applied stochastic model of the quality–quantity trade-off in the public health care sector

It is a striking feature of the many of the developing country public service sectors that the sectors in question often overproduce the quantity of services but underproduce the quality. This feature, which is exemplified in this paper, is rooted in a wide spectrum of economic and sociological factors ranging from the economic and sociological profile of the service receiving people to the asymmetric density of service-receiving population across their regions. This feature, we conjecture, is a source of a considerable degree of suboptimality in some of the developing countries. If our conjecture is correct, correcting such suboptimalities is likely to yield significant welfare improvements that could help speed up the process of development in the underdeveloped regions of the world. To analyze the supoopimalites in question, we will first develop a concept (and a model) of optimal quality in the public service sector, which indicates the level of quality that maximizes expected public satisfaction subject to available resources. Resources are used in an efficient manner to produce the service in question. The concept and the model in the paper make a needed contribution to the quality discourse by presenting a way of determining the quality improvements (or adjustments) necessary to achieve optimum in the public service sector. The paper presents an application (a case study) of this new concept in the public healthcare sector in Turkey, and explores the differences between the actual and optimal quality in the sector in question. It turns out that there is a considerable difference between the actual and optimal levels of quality (as well as those of quantity) in the Turkish public healthcare sector in an overpopulated city (Istanbul), indicating a significant overproduction of quantity and underproduction of quality. Thus, to achieve the optimal levels, the sector should increase quality and reduce quantity by a considerable margin. The quantified differences (gaps) between actual and optimal levels point out a considerable room for welfare improvement. Optimum-seeking adjustments closing these gaps could be shown to lead to considerable satisfaction and welfare gains, the measurement of which is worthy of future research.     

A model for irreversible investment with construction and revenue uncertainty

This paper presents a model of investment in projects that are characterized by uncertainty over both the construction costs and revenues. Both processes are modeled as spectrally negative Lévy jump-diffusions. The optimal stopping problem that determines the value of the project is solved under fairly general assumptions. It is found that the current value of the benefit-to-cost ratio (BCR) decreases in the frequency of negative shocks to the construction process. This implies that the cost overruns that can be expected if one ignores such shocks are increasing in their frequency. Based on calibrated data, the model is applied to the proposed construction of high-speed rail in the UK and it is found that its economic case cannot currently be made and is unlikely to be met at any time in the next decade. In addition it is found that ignoring construction uncertainty leads to a substantial probability of an erroneous decision being taken.     

Lottery versus all-pay auction contests: A revenue dominance theorem

We allow a contest organizer to bias a contest in a discriminatory way; i.e., she can favor specific contestants by designing the contest rule in order to maximize total equilibrium effort (resp. revenue). The two predominant contest regimes are considered, all-pay auctions and lottery contests. For all-pay auctions the optimal bias is derived in closed form: It implies extreme competitive pressure among active contestants and low endogenous participation rates. Moreover, the exclusion principle advanced by Baye et al. (1993) becomes obsolete in this case. In contrast, the optimally biased lottery induces a higher number of actively participating contestants due to softer competition. Our main result regarding total revenue comparison under the optimal biases reveals that the all-pay auction revenue-dominates the lottery contest for all levels of heterogeneity among contestants. The incentive effect due to a strongly discriminating contest rule (all-pay auction) dominates the participation effect due to a weakly discriminating contest rule (lottery).     

Optimal emission-extraction policy in a world of scarcity and irreversibility

This paper extends the classical exhaustible-resource/stock-pollution model with irreversibility of pollution decay, meaning that after reaching some threshold there is no decay of the pollution stock. Within this framework, we answer the question how the potential irreversibility of pollution affects the extraction path. We investigate the conditions under which the economy will optimally adopt a reversible policy, and when it is optimal to enter the irreversible region. In the case of irreversibility it may be optimal to leave a positive amount of resource in the ground forever. As far as the optimal extraction/emission policy is concerned, several types of solutions may arise, including solutions where the economy stays at the threshold for a while. Given that different programs may satisfy the first order conditions for optimality, we further investigate when each of these is optimal. We show that it is never optimal for the economy to stay at the threshold for a while before entering the irreversible region. The optimality analysis is then illustrated by means of a calibrated example. To sum up, for any pollution level, we can identify a critical resource stock such that there exist multiple optima i.e. a reversible and an irreversible policy that yield exactly the same present value. For any resource stock below this critical value, the optimal policy is reversible whereas with large enough resources, irreversible policies outperform reversible programs.     

Reconciling economic and biological modeling of migratory fish stocks: Optimal management of the Atlantic salmon fishery in the Baltic Sea

The paper puts forward a model of the Atlantic salmon fishery in the Baltic Sea that integrates the salient biological and economic characteristics of migratory fish stocks. Designed to be compatible with the framework used for actual stock assessments, the model accounts for age-structured population dynamics, the seasonal harvest and competing harvesting by commercial and recreational fishermen. It is parameterized for the Simojoki River stock. The socially optimal policy for maximizing discounted net benefits from the fishery within an uncertain environment is determined using a dynamic programming approach and numerical solution method. Our results indicate that substantial economic benefits could be realized under optimal management without compromising stock sustainability.     

Tax-tariff reform with costs of tax administration

As is broadly recognised, the straightforward application of the Diamond–Mirrlees (1971) production efficiency theorem implies that when lump-sum taxation is not available, then it is optimal for the government in a small open economy to rely on taxes on the net demand of households rather than on border taxes to finance its resource requirements. However, the theorem does not hold when taxation is associated with administrative costs. The present paper explores the implications for optimal taxation and for desirable directions of tax-tariff reform of taking into account the costs of tax administration in countries at different levels of economic development. The paper clarifies the reasons for, and lends support to, the criticism by Stiglitz (Presentation to Congress of International Institute of Public Finance, Prague, 2003) of the IMF and the World Bank’s recommendation to developing countries to adopt VAT to replace border taxes.      

Option hedging theory under transaction costs

The problem of option hedging in the presence of proportional transaction costs can be formulated as a singular stochastic control problem. Hodges and Neuberger [1989. Optimal replication of contingent claims under transactions costs. Review of Futures Markets 8, 222–239] introduced an approach that is based on maximization of the expected utility of terminal wealth. We develop a new algorithm to solve the corresponding singular stochastic control problem and introduce a new approach to option hedging which is closer in spirit to the pathwise replication of Black and Scholes [1973. The pricing of options and corporate liabilities. Journal of Political Economy 81, 637–654]. This new approach is based on minimization of a Black–Scholes-type measure of pathwise risk, defined in terms of a market delta, subject to an upper bound on the hedging cost. We provide an efficient backward induction algorithm for the problem of cost-constrained risk minimization, whose associated singular stochastic control problem is shown to be equivalent to an optimal stopping problem. This algorithm is then modified to solve the singular stochastic control problem associated with utility maximization, which cannot be reduced to an optimal stopping problem. We propose to choose an optimal parameter (risk-aversion coefficient or Lagrange multiplier) in either approach by minimizing the mean squared hedging error and demonstrate that with this “best” choice of the parameter, both approaches have similar performance. We also discuss the different notions of risk in both approaches and propose a volatility adjustment for the risk-minimization approach, which is analogous to that introduced by Zakamouline [2006. European option pricing and hedging with both fixed and proportional transaction costs. Journal of Economic Dynamics and Control 30, 1–25] for the utility maximization approach, thereby providing a unified treatment of both approaches.     

IV估计的最优工具变量选取方法

IV估计的有限样本性质对工具变量的选取十分敏感,尤其是存在弱工具变量的情形。本文在Donald和Newey(2001)的基础上研究了常用的IV估计———2SLS的最优工具变量选取方法。首先通过对2SLS估计量进行Nagar分解,从理论上推导出估计量的近似MSE表达式;根据这一表达式,提出IV估计的最优工具变量选取准则,并证明选取准则的渐近有效性。模拟结果表明,本文提出的工具变量选取准则能够极大地改善2SLS估计量的有限样本表现。本研究为实证中面临的工具变量选择问题提供了理论依据。     

Optimal monetary policy in a new Keynesian model with animal spirits and financial markets

This article presents a macro-finance-interaction model that integrates a NKM with bounded rationality and an agent-based financial market model. We derive four interactive channels between the two sectors where two channels are strictly microfounded. We analyze the impact of the different channels on economic stability and derive optimal (conventional and unconventional) monetary policy rules. We find that coefficients of optimal Taylor rules do not significantly change if financial market stabilization becomes part of the central bank׳s objective function. Additionally, we show that rule-based, backward-looking monetary policy creates huge instabilities if expectations are boundedly rational. Our model is externally validated by showing that it generates fat tailed output growth rates.     

Cash-in-advance constraint,optimal monetary policy,and human capital accumulation

This paper investigates optimal monetary policy in an overlapping-generations model with endogenous growth fueled by the accumulation of human capital and under a cash-in-advance constraint. We consider the case where the government finances public education fully by seigniorage. Three main results are obtained. First, there exists an optimal money growth rate that maximizes the economic growth rate along the steady growth path. Second, on this path, the Laffer curve of seigniorage takes the maximum. Finally, the money growth rate for maximizing seigniorage along the steady growth path, which also leads to maximization of the economic growth rate, is lower than that for maximizing seigniorage in the present period.