Regulation and efficiency in transition: the case of Romanian banks

Using disaggregated panel data for the period 1996–2002, this paper estimates the cost efficiency of Romanian banks and relates it to regulation implemented by the National Bank of Romania. We estimate efficiency using a model that combines the frameworks of both stochastic frontier analysis and shadow cost functions. Our results indicate that, for all types of banks, the cost of technical inefficiency decreases in the years following tightening of regulation. A significant part of this decrease can be attributed to the policy change. Overall, the short-run increase in cost due to additional regulation exceeds the benefits from reduced technical inefficiency. However, our model does not account for other benefits, besides changes in X-inefficiency, such as stability of the banking system, which may be significant.      

Container fleet sizing and empty repositioning in liner shipping systems

This paper considers the joint container fleet sizing and empty container repositioning problem in multi-vessel, multi-port and multi-voyage shipping systems with dynamic, uncertain and imbalanced customer demands. The objective is to minimize the expected total costs including inventory-holding costs, lifting-on/lifting-off costs, transportation costs, repositioning costs, and lost-sale penalty costs. A simulation-based optimization tool is developed to optimize the container fleet size and the parameterized empty repositioning policy simultaneously. The optimization procedure is based on Genetic Algorithms and Evolutionary Strategy combined with an adjustment mechanism. Case studies are given to demonstrate the results.     

Improving Tests of Abnormal Returns by Bootstrapping the Multivariate Regression Model with Event Parameters

Parametric dummy variable-based tests for event studies usingmultivariate regression are not robust to nonnormality of theresidual, even for arbitrarily large sample sizes. Bootstrapalternatives are described, investigated, and compared for caseswhere there are nonnormalities, and cross-sectional and time-seriesdependencies. Independent bootstrapping of residual vectorsfrom the multivariate regression model controls type I errorrates in the presence of cross-sectional correlation, and surprisingly,even in the presence of time-series dependence structures. Theproposed methods not only improve upon parametric methods, butalso allow development of new and powerful event study testsfor which there is no parametric counterpart.     

铸件热节动态变化特性的研究

本文采用计算机凝固数值模拟技术,研究铸件热节的位置、大小、形状和数量在凝固过程中随凝固时间的变化规律,揭示热节的动态性。     

A local search algorithm for the optimization of the stochastic economic lot scheduling problem

This paper describes a model for the stochastic economic lot scheduling problem (SELSP) and a Local Search heuristic to find close to optimal solutions to this model. The SELSP considers multiple products, which have to be scheduled on a single facility with limited capacity and significant setup times and costs. The demand is modeled as a stationary compound renewal process. The objective is to find a schedule that minimizes the long-run average costs for setups and inventories while satisfying a given fill rate. We use a cyclic scheduling approach in which the individual cycle time of each product is a multiple of some basic period (fundamental cycle).For the deterministic version of the SELSP, efficient heuristics have been developed which guarantee the feasibility of the solution by adding an additional constraint to the problem. In our case this is not sufficient, because for the calculation of the average inventory levels and fill rates we need to develop a schedule with detailed timing of the lots. We present an efficient heuristic for this scheduling problem, which can also be used to check the feasibility of the solution. Thereby, the most time-consuming step (the calculation of average inventory levels and fill rates) is only performed for a limited set of candidates.The algorithm was tested on deterministic benchmark problems from literature and on a large set of stochastic instances. We report on the performance of the heuristic in both cases and try to identify the main factors influencing the objective.     

Growing Silicon Valley on a landscape: an agent-based approach to high-tech industrial clusters

We propose a Nelson-Winter model with an explicitly defined landscape to study the formation of high-tech industrial clusters such as those in Silicon Valley. The existing literature treats clusters as the result of location choices and focuses on how firms may benefit from locating in a cluster. We deviate from this tradition by emphasizing that high-tech industrial clusters are characterized by concentrated entrepreneurship. We argue that the emergence of clusters can be explained by the social effect through which the appearance of one or a few entrepreneurs inspire many followers locally. Agent-based simulation is employed to show the dynamics of the model. Data from the simulation and the properties of the model are discussed in light of empirical regularities. Variations of the model are simulated to study policies that are favorable to the high-tech economy.JEL Classification: L11, R12This paper has been presented at the 9th International Schumpeter Society Conference in Gainesville, Florida, the Western Economic Associations 77th Annual Conference in Seattle, Washington, the 24th Annual Research Conference of the Association for Public Policy Analysis and Management in Dallas, Texas, and the Workshop on Industry and Labor Dynamics: The Agent-Based Computational Economics Approach in Turin, Italy. I would like to thank Rob Axtell, Giovanni Dosi, Olav Sorenson, and an anonymous referee for their comments, suggestions, and encouragement. I am grateful to Nikesh Patel for his superb assistance.     

A general revealed preference theorem for stochastic demand behavior

Summary. We present a general revealed preference theorem concerning stochastic choice behavior by consumers. We show that, when the consumer spends her entire wealth, the Weak Axiom of Stochastic Revealed Preference due to Bandyopadhyay, Dasgupta, and Pattanaik (1999) is equivalent to a restriction on stochastic demand behavior that we call stochastic substitutability. We also show that the relationship between the Weak Axiom of Revealed Preference and Samuelson's inequality in the deterministic theory, and the main result of Bandyopadhyay, Dasgupta, and Pattanaik (1999) are both special cases of our result.Received: 10 September 2001, Revised: 4 April 2003, JEL Classification Numbers: D11. Correspondence to: Prasanta K. PattanaikOur greatest debt is to the referee of this paper, who made numerous helpful suggestions. We thank Robin Cubitt, Kunal Sengupta and seminar audiences at Jawaharlal Nehru University, Indian Statistical Institute, University of East Anglia, Universidad Carlos III, University of Essex and University of Montreal for their helpful comments. Prasanta K. Pattanaik acknowledges his intellectual debt to Salvador Barbera, Tapas Majumdar and Amartya Sen.     

Estimation of technical inefficiency effects using panel data and doubly heteroscedastic stochastic production frontiers

In previous studies, measures of technical inefficiency effects derived from stochastic production frontiers have been estimated from residuals which are sensitive to specification errors. This study corrects for this inaccuracy by extending the doubly heteroscedastic stochastic cost frontier suggested by Hadri (1999) to the model for technical inefficiency effects. This model is a stochastic frontier production function for panel data as proposed by Battese and Coelli (1995). The study uses, for illustration of the techniques, data on 101 mainly cereal farms in England. We find that the correction for heteroscedasticity is supported by the data. Both point estimates and confidence intervals for technical efficiencies are provided. The confidence intervals are constructed by extending the “Battese-Coelli” method reported by Horrace and Schmidt (1996) by allowing the technical inefficiency to be time varying and the disturbance terms to be heteroscedastic. The confidence intervals reveal the precision of technical efficiency estimates and show the deficiencies of making inferences based exclusively on point estimates. First version received: March 2000/Final version received: Oct. 2001 RID="*" ID="*"  The authors are grateful to the Economic and Social Research Council for access to their Data Archive which has provided the data for this research. We are indebted to Badi Baltagi and two anonymous referees for their helpful comments and suggestions. The usual caveat applies.     

需求管理定向的小型中国宏观经济计量模型

本文使用OLS方法在 1 981— 2 0 0 1年间单方程估计中国IS LM AS模型 ,初步建立面向需求管理的小型中国宏观经济计量年度模型———CMAFM模型 ,并且在对CMAFM模型历史模拟检验的基础上进行中国财政政策和货币政策的动态乘数效应分析。