Variable selection for semiparametric proportional hazards model under progressive Type-II censoring

Variable selection is an effective methodology for dealing with models with numerous covariates. We consider the methods of variable selection for semiparametric Cox proportional hazards model under the progressive Type-II censoring scheme. The Cox proportional hazards model is used to model the influence coefficients of the environmental covariates. By applying Breslow’s “least information” idea, we obtain a profile likelihood function to estimate the coefficients. Lasso-type penalized profile likelihood estimation as well as stepwise variable selection method are explored as means to find the important covariates. Numerical simulations are conducted and Veteran’s Administration Lung Cancer data are exploited to evaluate the performance of the proposed method.     

Modification of GEE1 and linear mixed-effects models for heteroscedastic longitudinal Gaussian data

A characterization of GLMs is given. Modification of the Gaussian GEE1, modified GEE1, was applied to heteroscedastic longitudinal data, to which linear mixed-effects models are usually applied. The modified GEE1 models scale multivariate data to homoscedastic data maintaining the correlation structure and apply usual GEE1 to homoscedastic data, which needs no-diagnostics for diagonal variances. Relationships among multivariate linear regression methods, ordinary/generalized LS, naïve/modified GEE1, and linear mixed-effects models were discussed. An application showed modified GEE1 gave most efficient parameter estimation. Correct specification of the main diagonals of heteroscedastic data variance appears to be more important for efficient mean parameter estimation.     

关于渭河流域实施排污权交易制度的立法建议

从相关立法看,对渭河流域水污染的治理主要采取了传统的行政方式。为提高渭河水污染治理效率,促进陕西经济社会的可持续发展,有必要借鉴美国和我国上海、江苏等地比较成熟的做法,采用市场的方法即排污权交易来治理渭河流域水污染,这有利于促进企业技术革新,降低整个社会的治理成本,比单纯的行政方法更为迅速和有效。因此,应进行地方立法,规定可交易污染物的范围、排污权的初始分配方式、交易的程序等,以规范排污权交易市场;同时,确定渭河的环境容量总量以确定可供分配的指标,构建信息平台以降低交易费用及保障公民的知情权。     

张掖市虚拟水投入产出分析

 虚拟水战略是水资源社会化管理的一个重要途径。本文应用地区水资源投入产出模型,剔出外地调入品影响,通过本地完全需水系数,以及完全需水量与直接用水量比较,计算了张掖市产业间虚拟水的净转移以及区域虚拟水的调入调出,进一步构造了产业间虚拟水转移矩阵,清晰量化各产业间虚拟水的转移去向。结果表明,种植业及其他农业是虚拟水最大的净转移和输出部门,利用的水实际向制造业和畜牧业大量转移, 畜牧业又将种植业转移来的水大部分输出外地。通过量化经济部门之间对水资源需求的数量关联效应,从投入产出分析视角为张掖市水需求管理提供新的参考。     

Bootstrapping Malmquist Indices for Danish Seiners in the North Sea and Skagerrak

In connection with assessing how an ongoing development in fisheries management may change fishing activity, evaluation of Total Factor Productivity (TFP) change over a period, including efficiency, scale and technology changes, is an important tool. The Malmquist index, based on distance functions evaluated with Data Envelopment Analysis (DEA), is often employed to estimate TFP changes. DEA is generally gaining attention for evaluating efficiency and capacity in fisheries. One main criticism of DEA is that it does not have any statistical foundation, i.e. that it is not possible to make inference about DEA scores or related parameters. The bootstrap method for estimating confidence intervals of deterministic parameters can however be applied to estimate confidence intervals for DEA scores. This method is applied in the present paper for assessing TFP changes between 1987 and 1999 for the fleet of Danish seiners operating in the North Sea and the Skagerrak.     

简论李觏的土地思想

李觏是北宋中期重要的思想家,在李觏的整个思想体系中,经济思想占有很重要的地位。李觏非常重视土地问题,土地思想是李觏经济思想的核心。针对当时土地兼并日益激烈引起的社会危害,李觏也提出了关于土地问题的看法。他的土地思想经历了前后两个时期,前期主要从分配角度分析,主张平土均田。后期主要从生产角度批判土地兼并。李觏提出了＂平土均田＂、＂井田制＂、＂农业劳动力＂、＂尽地力、广垦辟＂、＂限田＂等抑制土地兼并,发展农业,保护农民利益的思想。     

The Italian Labour Force Survey to estimate fertility

The own-children method (OCM) applied to the Italian Labour Force Survey (ILFS) is an alternative way to give information on fertility for the years before the survey. By deriving children information and the population at risk on the basis of parents’ characteristics, a large-scale dataset for fertility analysis in Italy becomes available, also to reconstruct event histories. The quality assessment provided by comparing the total fertility rate (TFR) calculated on ILFS with the official regional and national TFRs by ISTAT gives us usable outcomes.     

Universal versus contextual effects on TQM: a triangulation study using neural networks

The objective of this study is to extend previous research on total quality management (TQM)-context-performance relationships and ‘fit’ using multiple methods. We combine artificial neural networks (ANNs) with structural equation modelling (SEM) to analyse several hypotheses and propositions. This is the first study in this area of research that utilises ANNs and a triangulation technique in the presence of several contextual factors. The SEM analyses suggest that company size and industry type may have contingency effects on some of the TQM practices and/or TQM-performance relationships. However, the ANN models have shown that these two contingency factors do not moderate TQM outcomes, implying that all organisations can benefit from TQM regardless of size and type. As well, these models show that formal TQM implementation and/or ISO certifications do not add any predictive power to the ANN models except in one case: TQM implementation and/or ISO certification added to organisational effectiveness and customer results to predict financial and market (F&M) results. The results further indicate that even though implementing TQM alone has a bigger impact on F&M results than obtaining ISO certification alone, combining the two will have an even greater impact on these results. Joint implementation leads to greater improvements in organisational effectiveness, which, in turn, has a positive effect on customer results and consequently F&M results. This is a unique finding within the context of moderator effects on TQM-performance relationships.     

Prevalence,incidence and risk factors of testosterone deficiency in a population-based cohort of men: results from the study of health in Pomerania

Objective.?Low total testosterone levels (TT) have been associated with increased morbidity and mortality. However, the prevalence and incidence of testosterone deficiency (TD) in association with its risk has not been assessed systematically to date.

Methods.?Data from the prospective population-based Study of Health in Pomerania were used. From the 2117 men aged 20–79 years at baseline, 1490 men with complete TT data were analysed. Crude and age-specific prevalence and incidence rates of TD were estimated by TT levels below the age-specific 10th percentile. Analysis of covariance and Poisson regression models were used to assess the association of socio-demographic characteristics, health-related lifestyle, as well as somatometric, medical and laboratory measures with risk of incident TD.

Results.?TD baseline prevalence was 10.4% (N?=?155) and incidence 11.7 per 1000 person-years. TT levels showed a significant age-related decline with an unadjusted rate of 0.05 nmol/l per year. Obesity, metabolic syndrome, diabetes and dyslipidaemia were identified as risk factors of incident TD. Subpopulations of men without the revealed risk factors at both examinations maintained constant TT levels over time.

Conclusions.?Besides aging alone, lifestyle and different comorbidities were associated with TT level decline, suggesting that the age-related TT decline may be at least partly prevented through the management of potentially modifiable risk factors and health related behaviour.     

Die Implementierung des Qualitätsmanagements in sozialen Einrichtungen

The implementation of quality management in social organizations. An evaluation of the results The article presents the results of an evaluation of the introduction prozess of the quality management in social organizations. In particular it illustrates the grounds of the specific features and differences of the participation procedures in this process. A prerequisite for a success is the bottom up procedere that recognizes and uses the resources, competencies and functions of the employees and managers. A formal optimizing of the operational processes will not induce a reorientation. If it does not succeed to internalize new approaches on the basis of a longterm learning process, the quality management will remain a paper and it will fail.