A new approach to statistical efficiency of weighted least squares fitting algorithms for reparameterization of nonlinear regression models

We study nonlinear least-squares problem that can be transformed to linear problem by change of variables. We derive a general formula for the statistically optimal weights and prove that the resulting linear regression gives an optimal estimate (which satisfies an analogue of the Rao-Cramer lower bound) in the limit of small noise.     

Small area estimation for longitudinal surveys

Over the last few years many studies have been carried out in Italy to identify reliable small area labour force indicators. Considering the rotated sample design of the Italian Labour Force Survey, the aim of this work is to derive a small area estimator which borrows strength from individual temporal correlation, as well as from related areas. Two small area estimators are derived as extensions of an estimation strategies proposed by Fuller (1990) for partial overlap samples. A simulation study is carried out to evaluate the gain in efficiency provided by our solutions. Results obtained for different levels of autocorrelation between repeated measurements on the same outcome and different population settings show that these estimators are always more reliable than the traditional composite one, and in some circumstances they are extremely advantageous.The present paper is financially supported by Murst-Cofin (2001) Lutilizzo di informazioni di tipo amministrativo nella stima per piccole aree e per sottoinsiemi della popolazione (National Coordinator Prof. Carlo Filippucci).     

A framework for progressively improving small area population estimates

Summary.  The paper presents a framework for small area population estimation that enables users to select a method that is fit for the purpose. The adjustments to input data that are needed before use are outlined, with emphasis on developing consistent time series of inputs. We show how geographical harmonization of small areas, which is crucial to comparisons over time, can be achieved. For two study regions, the East of England and Yorkshire and the Humber, the differences in output and consequences of adopting different methods are illustrated. The paper concludes with a discussion of how data, on stream since 1998, might be included in future small area estimates.     

Signed likelihood ratio tests in the Birnbaum-Saunders regression model

The Birnbaum-Saunders regression model is becoming increasingly popular in lifetime analyses and reliability studies. In this model, the signed likelihood ratio statistic provides the basis for testing inference and construction of confidence limits for a single parameter of interest. We focus on the small sample case, where the standard normal distribution gives a poor approximation to the true distribution of the statistic. We derive three adjusted signed likelihood ratio statistics that lead to very accurate inference even for very small samples. Two empirical applications are presented.     

A Bayesian predictive inference for small area means incorporating covariates and sampling weights

The main goal in small area estimation is to use models to ‘borrow strength’ from the ensemble because the direct estimates of small area parameters are generally unreliable. However, model-based estimates from the small areas do not usually match the value of the single estimate for the large area. Benchmarking is done by applying a constraint, internally or externally, to ensure that the ‘total’ of the small areas matches the ‘grand total’. This is particularly useful because it is difficult to check model assumptions owing to the sparseness of the data. We use a Bayesian nested error regression model, which incorporates unit-level covariates and sampling weights, to develop a method to internally benchmark the finite population means of small areas. We use two examples to illustrate our method. We also perform a simulation study to further assess the properties of our method.     

洪武永乐时期明朝与西域诸“地面”的关系

明初西域除东察合台汗国和帖木儿帝国两个势力强大的帝国外,还有一些大小不等的“地面”,学界对诸“地面”则鲜有涉猎.洪武永乐时期,与明朝关系相对密切的当是在东察合台汗国控制下的土鲁番、哈刺火州、柳城和于阗等.这一时期,瓦刺进入西域,并与东察合台汗国展开了角逐,瓦剌在西域地区的兴衰变化不仅对当时西域局势产生重要影响,而且对以后西域历史的发展影响深远.     

基于DEA方法的我国中小保险企业核心竞争力研究

随着国内保险市场的逐步开放,我国保险企业特别是中小保险企业面临着越来越大的竞争压力,提高核心竞争力成为中小保险企业持续健康发展的必然选择。DEA（数据包络分析）方法作为管理科学与系统工程领域一项重要而有效的分析工具,利用C^2R模型和投入产出指标体系,对输入输出数据进行综合分析,提炼出综合效率的数量指标,并将决策因素进行定级排序,从而给决策者提供高效率的管理信息,为提升我国中小保险企业核心竞争力提供有效对策。     

南阳市地下水补源措施探讨

本文针对南阳市地下术的开采现状，研究了地下水降落漏斗的现状，指出地下水的补源措施．     

小产权房问题背后的道义经济学

从道义经济的视角探讨了农民赋予小产权房的价值追求,以区别于已有小产权房相关研究基础上的经济人假设.认为小产权房现象背后内嵌着农民有关社会公正、集体尊严等基本观点,是他们应对货币化、劳动力商品化的自我保护和社会反向运动。     

关于政府构建与完善中小企业支持体系的思考

中小企业的发展,在推进国有企业改革、解决下岗职工再就业、增加财政收入、搞活城乡经济和加快小城镇建设等方面发挥了不可替代的作用。在我国中小企业的发展中,长期存在着一些制约其快速发展的因素,迫切需要政府构建和完善中小企业支持体系,以推动中小企业的持续、健康发展。