An Empirical Test of Environmental Kuznets Curve for Water Pollution

The Environmental Kuznets Curve (EKC) on water pollution was investigated with both semiparametric and parametric models using watershed level data for the state of Louisiana, USA. The parametric model indicated the turning points within the range $10241–$12993, $6636–$13877, and $6467–$12758 for nitrogen (N), phosphorus (P), and dissolved oxygen (DO), respectively. However, only the parameters associated with N EKC were found to be significant. Model specification tests rejected parametric models in favor of semiparametric specification for P but not for N and DO.     

Semiparametric estimation and testing in a model of environmental regulation with adverse selection

We consider a principal–agent model of environmental regulation with adverse selection, where firms are regulated through contracts. We show how the model allows to recover information on structural cost parameters. We use a semiparametric method to estimate consistently such parameters without specifying the distribution of the agents private information. We also show how to check for the specification of the econometric model, as well as auxiliary parametric assumptions, by means of specification tests based on nonparametric estimation. Results are used to discuss a selection of economic issues related to environmental regulation.First version received: August 2002/Final version received: November 2003Previous versions of this work were presented at Seminaire INRA-IDEI, Toulouse, the conference on Applications of semiparametric methods for micro-data, Tilburg, and seminars at UC Berkeley, University of Wisconsin–Madison, CREST, and INRA-LEA. We are indebted to participants, and especially Michael Visser, for their comments. We thank two referees for helpful comments. Financial support from the Conseil Régional Midi-Pyrénées and from INRA is gratefully acknowledged.     

The exact density of a statistic related to the shape parameter of a gamma variate

The exact density of the statistic ln , where and denote, respectively, the arithmetic and the geometric means of a random sample from a two-parameter gamma distribution, is obtained in a computable form using the technique of the inverse Mellin transform. This statistic is related to the maximum likelihood estimator of the shape parameter of a gamma distribution.     

Misspecification Preferred: The Sensitivity of Inefficiency Rankings

Ruggiero (European Journal of Operational Research 115, 555–563. 1999) compared the two popular parametric frontier methods for cross-sectional data—the stochastic frontier and the corrected OLS—in a simulation study. He demonstrated that the inefficiency ranking accuracy of the established stochastic frontier is uniformly inferior to that of the misspecified Corrected OLS (COLS) (which lacks an error term). The reason for his result remains unclear, however. In this paper, a more extensive simulation study is therefore conducted to find out whether the superiority of COLS is simply due to small sample sizes or to poor performance of the inefficiency level estimator.JEL Classification: C1,C2,C5     

Manager bonding and the technical efficiency of cooperative credit unions-parametric and non-parametric analyses

We engage parametric and non-parametric approaches to analyze unbalanced data (2012–16) from 225 credit unions in Ghana. The non-parametric analysis involves using data envelopment analysis to assess the technical efficiency of the credit unions. We show that most of them are not technically efficient. The average five-year overall technical efficiency and pure technical efficiency scores of a credit union are 0.87 and 0.91 respectively. Targeted at inquiring whether manager bonding significantly connects with the technical efficiency of credit unions, the parametric analysis which involves the use of probit and logit regression techniques, shows that, generally, the bonding of managers hurts the technical efficiency of credit unions. We are, thus, led to the conclusion that bonding of managers may not be in the best interest of credit unions in Ghana.     

基于参数法的物流园区用地规模预测——以长沙市为例

随着物流业的快速发展,物流园区在各地蓬勃兴起。然而,我国物流园区开发建设在取得较大成功的同时,也存在规划上贪大求全、土地资源浪费、园区闲置率高等问题。以长沙为例,利用参数法预测长沙未来物流园区用地规模,可为物流园区用地规模预测提供参考。     

Extension of the Wald statistic to models with dependent observations

A generalization of the Wald statistic for testing composite hypotheses is suggested for dependent data from exponential models which include Lévy processes and diffusion fields. The generalized statistic is proved to be asymptotically chi-squared distributed under regular composite hypotheses. It is simpler and more easily available than the generalized likelihood ratio statistic. Simulations in an example where the latter statistic is available show that the generalized Wald test achieves higher average power than the generalized likelihood ratio test. Received: February 29, 2000     

Environmental Production Factors and Efficiency of Smallholder Agricultural Households: Using Non‐parametric Conditional Frontier Methods

External environmental factors play a significant role in the agricultural production of smallholder farmers. This is especially the case in developing countries where production is less technologically intensive. These factors are mainly exogenous and affect both the farmers’ input choices and the final output levels. However, previous studies of technical efficiency of smallholder agricultural production either ignore these factors or assume separability between environmental factors and input choice, which is often not the case in developing counties. Using data on smallholder farmers in Ethiopia, we relax this separability assumption and investigate the importance of external environmental factors in farmers’ performance and efficiency variation across regions. The empirical analysis is based on a non‐parametric conditional order‐m estimation method that relaxes some of the traditional strong assumptions in efficiency modeling and, more importantly, the separability between environmental factors and the choice of physical inputs. Using data from four major agricultural regions of Ethiopia, we show the extent that environmental factors contribute to the technical efficiency and the significance of environmental factors in farmers’ performance.     

面向大规模定制的散热器产品集成平台优化设计系统

为解决散热器企业的快速设计问题,根据大规模定制模式的设计特点,提出面向大规模定制的散热器产品集成平台优化设计方法。阐述了散热器产品快速设计的实现过程,重点解决散热器产品参数化过程、平台模型库的建立、关键技术和总体功能等问题。设计并开发面向大规模定制的散热器产品集成平台优化设计系统。最后,以顾客参与的NVP3型散热器设计为例,验证了该系统在散热器产品快速设计方面的可行性。     

A Review on Modal Clustering

In spite of the current availability of numerous methods of cluster analysis, evaluating a clustering configuration is questionable without the definition of a true population structure, representing the ideal partition that clustering methods should try to approximate. A precise statistical notion of cluster, unshared by most of the mainstream methods, is provided by the density‐based approach, which assumes that clusters are associated to some specific features of the probability distribution underlying the data. The non‐parametric formulation of this approach, known as modal clustering, draws a correspondence between the groups and the modes of the density function. An appealing implication is that the ill‐specified task of cluster detection can be regarded to as a more circumscribed problem of estimation, and the number of clusters is also conceptually well defined. In this work, modal clustering is critically reviewed from both conceptual and operational standpoints. The main directions of current research are outlined as well as some challenges and directions of further research.