Efficient Estimation of Parameters of the Negative Binomial Distribution

In this article we investigate a class of moment-based estimators, called power method estimators, which can be almost as efficient as maximum likelihood estimators and achieve a lower asymptotic variance than the standard zero term method and method of moments estimators. We investigate different methods of implementing the power method in practice and examine the robustness and efficiency of the power method estimators.     

Incorporating quality into data envelopment analysis of nursing home performance: A case study

When using data envelopment analysis (DEA) as a benchmarking technique for nursing homes, it is essential to include measures of the quality of care. We survey applications where quality has been incorporated into DEA models and consider the concerns that arise when the results show that quality measures have been effectively ignored. Three modeling techniques are identified that address these concerns. Each of these techniques requires some input from management as to the proper emphasis to be placed on the quality aspect of performance. We report the results of a case study in which we apply these techniques to a DEA model of nursing home performance. We examine in depth not only the resulting efficiency scores, but also the benchmark sets and the weights given to the input and output measures. We find that two of the techniques are effective in insuring that DEA results discriminate between high and low quality performance.     

Time Series Models for Count or Qualitative Observations

Time series sometimes consist of count data in which the number of events occurring in a given time interval is recorded. Such data are necessarily nonnegative integers, and an assumption of a Poisson or negative binomial distribution is often appropriate. This article sets ups a model in which the level of the process generating the observations changes over time. A recursion analogous to the Kalman filter is used to construct the likelihood function and to make predictions of future observations. Qualitative variables, based on a binomial or multinomial distribution, may be handled in a similar way. The model for count data may be extended to include explanatory variables. This enables nonstochastic slope and seasonal components to be included in the model, as well as permitting intervention analysis. The techniques are illustrated with a number of applications, and an attempt is made to develop a model-selection strategy along the lines of that used for Gaussian structural time series models. The applications include an analysis of the results of international football matches played between England and Scotland and an assessment of the effect of the British seat-belt law on the drivers of light-goods vehicles.     

On the use of the scholz-sievers method for dlstribution-free inference about the difference in slopes of two regression lines

A simple adaptation of a distribution-free method due to Scholz (1978) and Sievers (1978) for inference in a single regression setting is proposed for inference about the difference in slopes of two regression lines. We assume that the data are obtained from a designed experiment with common regression constants. A comparison of the proposed method to its competitors-one due to Hollander and the other due to Rao and Gore-indicates superiority of the new method.     

Efficiency determinants in retail stores: a Bayesian framework

This paper analyzes the impact of vertical integration, age, geographic expansion, and low price strategy on the cost efficiency of retail stores. We test our hypotheses using the innovative Bayesian frontier methodology. The data involve a sample of Spanish retail stores that operate in a highly competitive and dynamic environment. From the results, it is clear that cost efficiency is higher for stores that have: longer years in business, stronger geographical presence, and lower price offerings. Vertical integration, on the other hand, is negatively related to efficiency. Further discussions of these findings and related managerial implications are provided in the paper.     

On the asymptotic power and relative efficiency of the frequency X2 test

The asymptotic (Pitman) power of the X² test is investigated for particular classes of alternatives. A simple rule is introduced to identify ‘orthogonal alternatives’, for which the noncentrality parameter can be computed in a very simple way. In the sequel, restricted alternatives are considered and the ARE of the unrestricted test w.r.t. the restricted one is shown to depend only on the numbers of degrees of freedom. The concluding section discusses ‘undetectable alternatives’, i.e. alternatives for which the noncentrality vanishes.     

Inferences from Cross-Sectional,Stochastic Frontier Models

Conventional approaches for inference about efficiency in parametric stochastic frontier (PSF) models are based on percentiles of the estimated distribution of the one-sided error term, conditional on the composite error. When used as prediction intervals, coverage is poor when the signal-to-noise ratio is low, but improves slowly as sample size increases. We show that prediction intervals estimated by bagging yield much better coverages than the conventional approach, even with low signal-to-noise ratios. We also present a bootstrap method that gives confidence interval estimates for (conditional) expectations of efficiency, and which have good coverage properties that improve with sample size. In addition, researchers who estimate PSF models typically reject models, samples, or both when residuals have skewness in the “wrong” direction, i.e., in a direction that would seem to indicate absence of inefficiency. We show that correctly specified models can generate samples with “wrongly” skewed residuals, even when the variance of the inefficiency process is nonzero. Both our bagging and bootstrap methods provide useful information about inefficiency and model parameters irrespective of whether residuals have skewness in the desired direction.     

ICT投资、互联网普及和全要素生产率

本文使用DEA-Malmquist指数方法对2002-2012年我国分行业全要素生产率、技术效率与技术进步进行测算,并基于我国地区投入产出表构建了ICT资本投入强度。在此基础上,本文就ICT投资对生产率的影响进行了实证检验。研究发现,ICT投资对全要素生产率提升具有积极作用,并且主要通过ICT投资促进技术效率提升实现。面板门限回归模型的结果显示,只有达到一定互联网普及率时,ICT投资促进技术效率提升的作用才显现,并在高互联网普及率时进一步增强;但在高互联网普及率下,ICT 投资对技术进步存在抑制作用,在全要素生产率层面表现为ICT 投资的促进作用消失。因此,现实的ICT 投资应重视通过信息化管理提升行业资源的有效利用能力,以最大化技术效率对全要素生产率的贡献;应充分考虑不同行业和地区的互联网普及程度,以深度激发“连接经济”对于释放ICT效能的互补性作用;还应注意配套相应产业政策,以减轻互联网发展对技术进步的阻碍作用。     

“效率优先,兼顾公平”究竟错在哪里

在特定的历史时期,“效率优先,兼顾公平”的提法对于破除计划经济体制和平均主义观念起了积极的作用。随着中国发展进程的推进,这一提法逐渐显露出其明显的局限性,主要表现在:同以人为本的基本理念相抵触;没有区分基本制度和具体政策2个层面的公正问题;与和谐社会建设格格不入;将这一提法泛化并覆盖非经济领域;意味着现代政府主要职能的错位;对初次分配重效率、再次分配重公平的定位有误。从长远看,这一提法对中国社会经济的发展会产生广泛的负面影响:对现代社会的制度建设不利;对改革和发展的有机统一不利;对公正合理的社会结构的形成不利;延缓了合理、健全的社会政策的制定。正确的提法应当是:以社会公正为基本理念和基本准则,促进社会经济的协调发展,促进改革开放和现代化建设的整体化推进,促进和谐社会的建设。     

中国能源消费静态依赖与动态发展——基于30个省市数据综列协整分析

本文以我国30个省市为横截单元、以1995-2005年时序数据组成综列数据,建立我国省市能源消费的综列协整模型,通过综列单位根和综列协整检验,结果表明,我国各省市的能源消费与经济增长和能源效率之间存在长期均衡。基于这一结论,揭示各省市能源消费静态依赖与动态发展特征,并给出政策建议。