Comparative performance measurement in regulation: the case of English and Welsh sewerage services

This paper discusses the use of comparative performance measurement by means of Data Envelopment Analysis in the context of the regulation of English and Welsh water companies. Specifically, the use of Data Envelopment Analysis to estimate potential cost savings in sewerage is discussed as it fed into the price review of water companies carried out by the regulator of water companies in 1994. The application is used as a vehicle for highlighting generic issues in terms of assessing the impact of factors on the ranking of units on performance, the insights gained from using alternative methods to assess comparative performance, and the issue of assessing comparative performance when few in number but highly complex entities are involved. The paper should prove of interest to those interested in regulation and, more generally, in the use of methods of comparative performance measurement.     

On simulation-based approaches to risk measurement in mortality with specific reference to Poisson Lee-Carter modelling

This paper provides a comparative study of simulation strategies for assessing risk in mortality rate predictions and associated estimates of life expectancy and annuity values in both period and cohort frameworks.     

DEA as a tool for bankruptcy assessment: A comparative study with logistic regression technique

This paper proposes data envelopment analysis (DEA) as a quick-and-easy tool for assessing corporate bankruptcy. DEA is a non-parametric method that measures weight estimates (not parameter estimates) of a classification function for separating default and non-default firms. Using a recent sample of large corporate failures in the United States, we examine the capability of DEA in assessing corporate bankruptcy by comparing it with logistic regression (LR). We find that DEA outperforms LR in evaluating bankruptcy out-of-sample. This feature of DEA is appealing and has practical relevance for investors. Another advantage of DEA over LR is that it does not have assumptions associated with statistical and econometric methods. Furthermore, DEA does not need a large sample size for bankruptcy evaluation, usually required by such statistical and econometric approaches. The need for such a large sample size is a significant disadvantage to practitioners when investment decisions are made using small samples. DEA can bypass such a difficulty related to a sample size. Thus, DEA is a practically appealing method for bankruptcy assessment.     

Spatial econometric approach to the EU regional employment process

This paper deals with the estimation of spatial econometric models of employment rate across 259 NUTS 2 (Nomenclature of Units for Territorial Statistics) regions of the European Union in 2018 regarding different region-specific factors. Since, spatial autocorrelation and spatial heterogeneity often occur jointly, the paper is oriented at verification of two hypotheses. Hypothesis 1 related to the existence of the spatial autocorrelation, i.e., that the regional employment process is not a spatially isolated process, was confirmed. Based on the estimation of Spatial Durbin Model, direct, indirect and total spatial impacts were quantified and verified. The results proved the significant impact of neighbouring regions for GDP and compensation of employees variables in explaining regional employment rate. Significant influence of factors like educational attainment level and population density seems to be limited only to the particular region. Hypothesis 2 reflected the existence of the spatial heterogeneity. Based on the geographically weighted regression the assumption of spatial variability of the model parameters was also verified. The regional employment in the EU seems to be affected by both spatial effects and the presented approaches thus represent two different insights into the complex spatial character of the modelled process.

     

Computing the complete CS decomposition

An algorithm for computing the complete CS decomposition of a partitioned unitary matrix is developed. Although the existence of the CS decomposition (CSD) has been recognized since 1977, prior algorithms compute only a reduced version. This reduced version, which might be called a 2-by-1 CSD, is equivalent to two simultaneous singular value decompositions. The algorithm presented in this article computes the complete 2-by-2 CSD, which requires the simultaneous diagonalization of all four blocks of a unitary matrix partitioned into a 2-by-2 block structure. The algorithm appears to be the only fully specified algorithm available. The computation occurs in two phases. In the first phase, the unitary matrix is reduced to bidiagonal block form, as described by Sutton and Edelman. In the second phase, the blocks are simultaneously diagonalized using techniques from bidiagonal SVD algorithms of Golub, Kahan, Reinsch, and Demmel. The algorithm has a number of desirable numerical features.      

New Alternating Direction Method for a Class of Nonlinear Variational Inequality Problems

The alternating direction method is an attractive method for a class of variational inequality problems if the subproblems can be solved efficiently. However, solving the subproblems exactly is expensive even when the subproblem is strongly monotone or linear. To overcome this disadvantage, this paper develops a new alternating direction method for cocoercive nonlinear variational inequality problems. To illustrate the performance of this approach, we implement it for traffic assignment problems with fixed demand and for large-scale spatial price equilibrium problems.     

Separating Market Efficiency from Profitability and its Implications for Planning

This paper discusses the practical usefulness of separating market efficiency from profitability when assessing the comparative performance of private sector organizational units. The market efficiency of a unit reflects its ability to attract custom. The paper shows how data envelopment analysis can be used to assess market efficiency and it illustrates the usefulness of this measure in managing the public houses of a brewery.     

A FEM-BEM approach for Fluid-Structure Interaction

In an earlier attempt to solve problems of Fluid-Structure Interaction (FSI), a high-order finite element code, which can be applied to solve problems of Computational Structural Dynamics (CSD) has been coupled to a Lattice Boltzmann (LB) fluid solver. In order to extend this approach to maritime applications and to increase the computational efficiency, the CSD solver is coupled to a fluid solver based on the Boundary Element Method (BEM). In this way, the computational effort for the discretisation of the fluid is significantly reduced. In this paper the proposed coupling scheme is discussed and compared to a FSI scheme where the BEM is replaced by a method based on the Reynolds-averaged Navier-Stokes equations (RANSE). Special emphasis is placed on the question of how to exchange the data between the different discretisation schemes and the development of a stable and efficient coupling scheme for FSI simulations. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

空间影响与环境库兹涅茨曲线:基于空间经济计量方法的实证分析

本文选取中国及周边21个国家和地区基于能源消费的二氧化碳排放量作为环境污染指标,利用空间经济计量方法对中国及其周边国家和地区的环境库兹涅茨曲线进行估计,估计结果显示空间影响显著存在。因此政府在制定环境政策时,不能只考虑本国或本地区的自身要素条件,还要充分分析和利用周边国家和地区的自然和技术条件。     

我国普通高等教育人力资源发展水平的统计分析

本文综合运用主成分分析和因子分析两种综合评价方法 ,对我国各地区高等教育人力资源的发展水平进行排序和分类 ,为规划和发展各地区的高等教育事业提供了一定的科学依据。两种综合评价方法的综合运用克服了单一评价方法的片面性 ,评价结果较为全面、客观     

Parameter domains for spots and stripes in mechanical models for biological pattern formation

Summary Mechanochemical models for biological pattern formation have been applied to the development of a variety of patterning problems, such as feather germ primordia and cartilage formation in the vertebrate limb. Linear analysis has been the main technique for assessing the pattern formation potential of these models to date. In this paper we carry out a nonlinear analysis and numerical simulations of a generic model in two spatial dimensions. With these methods, we obtain conditions for generating specific spatial patterns such as stripes and spots, and divide the parameter space into domains giving rise to distinct types of pattern. We accomplish our goal through a study of model parameter domains by showing how different mechanical forces affect spatial patterning.     

R&D投入、技术溢出及吸收能力与经济增长的空间计量分析

利用我国31个省份2001-2010年的面板数据,使用空间滞后模型(SLM)研究了我国区域RD投入、空间溢出效应及吸收能力对经济增长的影响.研究结果表明我国各省份经济增长之间存在着高度的空间相关性,一个省份的RD投入不仅能够促进本地区的经济增长,还会通过技术溢出促进相邻地区的经济增长,同时一个地区吸收能力越强,其对该地区经济增长的影响也越大.     

涟漪效应还是空间互动——基于空间面板联立方程模型的房价与地价关系研究

本文通过构建包含房价和地价在内的空间面板联立方程模型,利用2009～2016年中国286个地市的数据,构建空间面板联立方程模型,以研究房价和地价的空间自相关性和空间溢出效应。实证结果表明：房价与地价之间的空间互动作用明显,房价不但受到当地地价的影响还会受到周边城市房价的影响;而城市地价也会受到当地房价引起的引致需求影响,并且受到周边城市地价的影响。分区域来看,地价对房价的作用强度在东、中、西部地区依次下降,房价对地价作用强度呈现出相反的趋势。而从价格的溢出效应来看,无论是房价还是地价,西部地区的价格溢出效应都最为明显,表明相对于东、中部地区,西部地区城市在房价和地价上都更会受到周围城市的影响。     

Healing times for circular wounds on plane and spherical bone surfaces

A mathematical model is developed for the rate of healing of a circular wound in a spherical “skull”. The motivation for this model is based on experimental studies of the “critical size defect” (CSD) in animal models; this has been defined as the smallest intraosseous wound that does not heal by bone formation during the lifetime of the animal [1]. For practical purposes, this timescale can usually be taken as one year. In [2], the definition was further extended to a defect which has less than ten percent bony regeneration during the lifetime of the animal. CSDs can “heal” by fibrous connective tissue formation, but since this is not bone, it does not have the properties (strength, etc.) that a completely healed defect would. Earlier models of bone wound healing [3,4] have focused on the existence (or not) of a CSD based on a steady-state analysis, so the time development of the wound was not addressed. In this paper, the time development of a circular cylindrical wound is discussed from a general point of view. An integro-differential equation is derived for the radial contraction rate of the wound in terms of the wound radius and parameters related to the postulated healing mechanisms. This equation includes the effect of the curvature of the (spherical) skull, since it is clear from the experimental evidence that the size of the CSD increases monotonically with the size of the calvaria. Certain special cases for a planar wound are highlighted to illustrate the qualitative features of the model, in particular, the dependence of the wound healing time on the initial wound size and the thickness of the healing rim.     

Comparison on five estimation approaches of intensity for a queueing system with short run

Traffic intensity is an important measure for assessing performance of a queueing system. In this paper, we propose a consistent and asymptotically normal estimator (CAN) of intensity for a queueing system with distribution-free interarrival and service times. Using this estimator and its estimated variance, a 100(1 ? α)% asymptotic confidence interval of the intensity is constructed. Also, four bootstrap approaches—standard bootstrap, Bayesian bootstrap, percentile bootstrap, and bias-corrected and accelerated bootstrap are also applied to develop the confidence intervals of the intensity. A comparative analysis is conducted to demonstrate performances of the five confidence intervals of the intensity for a queueing system with short run data.     

Comparative regional GDP analysis: case study of Croatia

The focus of this paper is the regional GDP analysis of Croatian Counties. It is a part of an extensive on-going scientific research about Croatian economic challenges within the global recession environment. Although, as EU accession country, Croatia is divided into three NUTS 2 regions, twenty one Croatian Counties show significant economic and social disproportions. In multiple regression model it is researched to what extent regional GDP per capita depends on a set of regional variables (employment, gross investment, production of more important agricultural products, GVA per person employed, construction works value, exports, imports, foreign tourists arrivals, foreign tourist nights, ecology...). Subsequently parameters are evaluated by Monte Carlo simulations which are used for the first time in comparative regional analysis. Also Croatian Counties are classified using Cluster analysis to make a comparative analysis with official spacing into three NUTS 2 regions which are geographical and political areas rather than real and homogenous socio-economic areas.     

Comparison of recurrence quantification methods for the analysis of temporal and spatial chaos

A comparative study of the recurrence properties of time series and two-dimensional spatial data is performed by means of Recurrence Quantification Analysis. The recent extension to distributed data of methods based on recurrences reveals new insights improving the performances of the approach for the analysis of complex spatial patterns. Indeed, the measures determinism and entropy provide significant information about the small and large scale characterization of the patterns allowing for a better connection to the physical properties of the spatial system under investigation.     

Asymptotic analysis of simultaneous damages in spatial Boolean models

A notion of the positive spatial association is introduced in this paper to analyze spatial dependence of Boolean models with the focus on estimating the long-range spatial dependence. The explicit tail estimates for probabilities of simultaneous damage to two distant spatial regions are obtained using the regular variation method, and the long-range spatial covariance for the Boolean models with heavy-tailed grains is shown to decay at the power-law rate that is smaller than the tail decay rate of grains. Examples and applications to spatial reliability modeling are also discussed.     

A Comparison of Regression Analysis and Data Envelopment Analysis as Alternative Methods for Performance Assessments

This paper compares regression analysis and data envelopment analysis as two alternative methods for assessing the comparative performance of homogeneous organizational units such as bank branches or schools. The comparison is restricted to units using a single resource or securing a single output. It focuses on the estimates of relative efficiency, marginal input-output values and target input-output levels that the two methods offer. A set of hypothetical hospitals is used to illustrate the performance of the two methods. It is found that, in general, data envelopment analysis outperforms regression analysis on accuracy of estimates but regression analysis offers greater stability of accuracy.     

视频监控系统中运动目标的阴影消除

本文通过分析阴影的像素特征,建立了一个关于目标帧与背景帧的对比帧来实现阴影监测和消除.为了研究问题方便,本文只考虑视频系统中的摄像头是固定位置的,并且检测目标区域中的较大阴影.利用光流法技术和背景差方法,运动目标能被快速准确的提取出来.同时,背景帧、前景帧及它们的对比帧也被提取出来,而对比帧具有更好的阴影特征.在对比帧上,可以使用静态图像处理技术的一些高效算法,来实时检测阴影区域.本文提出一个对比帧的建立方法,并进一步利用水平集方法来定位阴影区域和消除阴影.通过实验,在选择合适的阈值下,该方法是有效而快速的.