基于SE-Malmquist模型的农业生产率分析——以新疆为例

运用超效率模型计算Malmquist指数,测算出2004-2007年新疆农业全要素生产率不断提高,对Malmquist指数进行分解以分析其不断提高的原因.结果表明,新疆农业生产率的提高是由技术进步推动的结果,技术效率变化率没有发挥促进作用;各地区农业生产效率差距较大;农业生产效率与技术进步没有很好地结合.为进一步提高新疆农业生产率,需要充分挖掘现有技术潜力,做好现有技术的推广运用.     

Conditional variance estimation in heteroscedastic regression models

First, we propose a new method for estimating the conditional variance in heteroscedasticity regression models. For heavy tailed innovations, this method is in general more efficient than either of the local linear and local likelihood estimators. Secondly, we apply a variance reduction technique to improve the inference for the conditional variance. The proposed methods are investigated through their asymptotic distributions and numerical performances.     

企业组织创新与生产率关系的实证研究：以纺织业为例的讨论

本文结合国际创新实证研究新动态,在将创新定义扩展的基础上,以纺织业为例,分析组织创新对于企业生产率的影响。实证研究表明,在企业分规模、分经济类型和分地区的情况下,组织创新对于企业生产率的提高具有显著的影响,只是影响程度各有不同。因此,促进企业组织创新,拓展对创新观念的认识,从而提高企业生产率是应当考虑的企业增长路径之一。     

组织支持、组织文化认同和情绪工作作用机制研究

以服务行业工作人员为研究对象,通过实证分析对组织支持、组织文化认同和情绪工作间的作用机制进行研究。结果表明：同事支持、上级支持和企业支持对表层行为有显著负向影响,上级支持和企业支持对深层行为有显著正向影响;组织文化认同的行为性认同维度对表层行为有抑制作用,认知性认同、情感性认同和行为性认同则能有效激发员工的深层行为;组织支持通过组织文化认同的部分中介作用对表层行为和深层行为产生影响。     

An efficient sequential design of clinical trials

We propose an efficient group sequential monitoring rule for clinical trials. At each interim analysis both efficacy and futility are evaluated through a specified loss structure together with the predicted power. The proposed design is robust to a wide range of priors, and achieves the specified power with a saving of sample size compared to existing adaptive designs. A method is also proposed to obtain a reduced-bias estimator of treatment difference for the proposed design. The new approaches hold great potential for efficiently selecting a more effective treatment in comparative trials. Operating characteristics are evaluated and compared with other group sequential designs in empirical studies. An example is provided to illustrate the application of the method.     

Variable Selection for Partially Linear Models with Randomly Censored Data

This article proposes a variable selection procedure for partially linear models with right-censored data via penalized least squares. We apply the SCAD penalty to select significant variables and estimate unknown parameters simultaneously. The sampling properties for the proposed procedure are investigated. The rate of convergence and the asymptotic normality of the proposed estimators are established. Furthermore, the SCAD-penalized estimators of the nonzero coefficients are shown to have the asymptotic oracle property. In addition, an iterative algorithm is proposed to find the solution of the penalized least squares. Simulation studies are conducted to examine the finite sample performance of the proposed method.     

Partially Accelerated Life Tests for the Weibull Distribution Under Multiply Censored Data

This article aims to estimate the parameters of the Weibull distribution in step-stress partially accelerated life tests under multiply censored data. The step partially acceleration life test is that all test units are first run simultaneously under normal conditions for a pre-specified time, and the surviving units are then run under accelerated conditions until a predetermined censoring time. The maximum likelihood estimates are used to obtaining the parameters of the Weibull distribution and the acceleration factor under multiply censored data. Additionally, the confidence intervals for the estimators are obtained. Simulation results show that the maximum likelihood estimates perform well in most cases in terms of the mean bias, errors in the root mean square and the coverage rate. An example is used to illustrate the performance of the proposed approach.     

A Quality Control Approach of PVC Gloves Based on the Integration of SPC and EPC

Parameters in the production process of PVC gloves, such as production cycle, oven temperature, temperature, and viscosity of feed liquids are critical to the final quality of gloves. The dosing of feed liquids and plasticization of gloves are all controlled manually, and the viscosities of feed liquids and average oven temperature cannot be exactly regulated; those result in the degradation of final products and unreliability of the process. This article conducted studies on reliability enhancement of glove quality—an integrated control policy based on SPC and EPC was raised to minimize the process fluctuation, stabilize the output quality, and finally improve the process reliability. Using SPC method to eliminate the assignable factors in the process, when the process is under control, the EPC method was applied to make the process parameters closer to the target values which were decided through an inverse model of the process. The theory and methods were verified in the case study of PVC production control.     

Is the Selected Population the Best?—Location and Scale Parameter Cases

We observe X ₁,…,X _k , where X _i has density f(x,θ _i ) possessing monotone likelihood ratio. The best population corresponds to the largest θ _i . We select the population corresponding to the largest X _i . The goal is to attach the best possible p-value to the inference: the selected population has the uniquely largest θ _i . Gutmann and Maymin (1987 Gutmann , S. , Maymin , Z. ( 1987 ). Is the selected population the best? Ann. Statist . 15 : 456 – 461 .[Crossref], [Web of Science ®] , [Google Scholar]) considered the location parameter case and derived the supremum of the error probability by conditioning on S, the index of the largest X _i . Using this conditioning approach, Kannan and Panchapakesan (2009 Kannan , N. , Panchapakesan , S. ( 2009 ). Does the selected normal population have the smallest variance? Amer. J. Math. Management Sci . 29 : To appear . [Google Scholar]) considered the problem for the gamma family. We consider here a unified approach to both the location and scale parameter cases, and obtain the supremum of the error probability without using conditioning.     

Asymptotocally nonparametric tests with censored paired data

A class of asymptotically nonparametric test with contains a test proposed by Wei(1980), is considered for testing the equality of two continuous distribution funcitons when paired observations are subject to arbitrary right censorship. It is shown that under the null hypothesis each test statistic converges in distribution to the standard normal random variable. Furthermore. the Monte Carlo simulation results indicate that some tests in this class are more powerful than Wei's test. A generalization to incomplete censored paired data is also included.