An efficient nonparametric estimator for models with nonlinear dependence

We provide a convenient econometric framework for the analysis of nonlinear dependence in financial applications. We introduce models with constrained nonparametric dependence, which specify the conditional distribution or the copula in terms of a one-dimensional functional parameter. Our approach is intermediate between standard parametric specifications (which are in general too restrictive) and the fully unrestricted approach (which suffers from the curse of dimensionality). We introduce a nonparametric estimator defined by minimizing a chi-square distance between the constrained densities in the family and an unconstrained kernel estimator of the density. We derive the nonparametric efficiency bound for linear forms and show that the minimum chi-square estimator is nonparametrically efficient for linear forms.     

On estimating the mean of the selected normal population under the LINEX loss function

Following Parsian and Farsipour (1999), we consider the problem of estimating the mean of the selected normal population, from two normal populations with unknown means and common known variance, under the LINEX loss function. Some admissibility results for a subclass of equivariant estimators are derived and a sufficient condition for the inadmissibility of an arbitrary equivariant estimator is provided. As a consequence, several of the estimators proposed by Parsian and Farsipour (1999) are shown to be inadmissible and better estimators are obtained. Received January 2001/Revised May 2002     

Pitfalls of Normal-Gamma Stochastic Frontier Models

Although conceptually pleasing, normal-gamma frontier models lead to difficult estimation problems. It is shown here that unless the sample size reaches several thousands of observations the shape parameter of the gamma density is hard to estimate, and that this carries over to estimates of the stochastic frontier, the individual inefficiencies, and the allocation of the overall variance to the stochastic frontier and to the inefficiencies.     

The topography of metropolitan employment: Identifying centers of employment in a polycentric urban area

While it is well recognized that US metropolitan areas are polycentric, there is little consensus as to the appropriate method for identifying concentrations of employment within them. Existing methods suffer from strong assumptions about parametric form, misspecification, or reliance on local knowledge to calibrate model parameters. This paper introduces a new nonparametric method for identifying subcenters. Results indicate that this, more flexible, nonparametric approach yields greater accuracy with regard to both urban and suburban centers compared with other approaches. This approach should provide better data for the numerous topics that depend on the spatial accounting of employment within metropolitan areas.     

Rationing in open economy and dynamic macroeconomics: A survey

Summary A survey of rationing in micro theories of macroeconomics is presented. The survey starts with a closed economy with money and inventories, which consists of a representative household, a firm and government. After a discussion of the notional demands and supplies and the properties of the Walrasian equilibrium, a discussion of the effective demands and supplies leads to an analysis of the four regimes (Keynesian unemployment, classical unemployment, repressed inflation and underconsumption). A fiscal and monetary contraction decreases sales and employment when there is Keynesian unemployment, but is expansionary (neutral) when there is repressed inflation (classical unemployment). The survey continues with an analysis of the effects of rationing in a small open economy. It considers the one-sector model and a model with a traded and a nontraded sector. The latter model is used to discuss the effects of an oil discovery on the Gulf countries and on Latin American countries. The survey ends with a discussion of rationing in dynamic economies, which leads to an analysis of the effects of expectations about future constraints on current regimes and to a discussion of boot-strap equilibria.The author is Director of the Network for Quantitative Economics. This paper is a brief and eclectic survey of rationing models of closed one-period and two-period economies and of small open economies. It contains no significant new material. The author is grateful to Professor Theo van de Klundert for his constructive comments on an earlier version of this survey.     

The role of extension in the development of the farmer as entrepreneur

Different viewpoints were expressed at the 1990 annual national conference of the South African Society for Agricultural Extension regarding the role of extension in the development of the farmer as entrepreneur. It is expected that public funding will increasingly be limited to functions of general public interest. To achieve independence farmers should be willing to expose themselves to entrepreneur development stimuli. it is in the public interest to develop scarce human, economic and natural resources. Research findings indicate distinct behavioral differences between entrepreneurs of differing perceptions. A comprehensive interdisciplinary education is recommended for agriculturalists. Because needs change, education programmes must be re‐evaluated from time to time. It serves little purpose to educate people in extension who do not have a technical message to communicate. The state extension service seeks closer cooperation and liaison with agricultural co‐operative and private sector know‐how. Departmental policy will probably be less rigid in future.

A clear distinction should be made between information and extension services. The adoption of an ethical code for extensionists may be opportune. Relevancy is an important contributing factor to extensionist credibility.     

Convergence in West German Regional Unemployment Rates

Abstract. Differences in regional unemployment rates are often used to describe regional economic inequality. This paper asks whether changes in regional unemployment differences in West Germany are persistent over time. Understanding the persistency of regional unemployment differences helps us to assess how effective regional policy can be. While univariate tests suggest that changes in regional unemployment differences are persistent in West Germany, more powerful panel tests lend some support to the hypothesis that regional unemployment rates converge. However, these tests reveal a moderate speed of convergence at best. Because there is a structural break following the second oil crisis, we also use tests that allow for such a break. This provides evidence for both convergence and quick adjustment to an equilibrium distribution of regional unemployment rates that is, however, subject to a structural break.