企业信息系统项目效率的评价方法研究

在简要总结信息系统评价方法的基础上,提出了应用改进的DEA模型客观评价企业信息系统项目效率的方法,建立了信息系统项目的投入和产出指标体系,并实证分析了大型陶瓷企业信息系统项目的相对效率.     

SMA路面施工应注意的问题

通过对改性沥青SMA面层试验段结果分析,从原材料、拌和、摊铺、碾压等方面对改性沥青及SMA混合料在施工中需要注意的问题及解决的方法进行了阐述。     

军机备件需求量修正的粗糙集方法

本文针对不可量化因素对军机备件需求量的影响,提出了基于粗糙集的备件需求量的修正方法。考虑不可量化因素存在多值性的问题,将不可分辨关系下的经典粗糙集方法拓展成相容关系下的扩展粗糙集方法,通过相容关系下的近似空间获取决策规则,再由决策规则得到修正系数。最后以轮胎类器材为例,说明了修正系数的获取过程。     

中国股市收益率分布特征研究

应用修正Weibull分布对上海综合指数收益率和深圳成分指数收益率的分布状况进行研究。结果表明:经过简单的移位变换后,上证综指收益率和深成指收益率可完全用修正Weibull分布来刻画;大收益率服从次指数分布,小收益率服从超指数分布;两股指收益率的概率分布存在一些差异,上证综指的波动性大于深成指的波动性;沪深股市收益率的分布在1996年以后发生了较大的变化,其中沪市变化更大。     

Modified likelihood ratio tests in heteroskedastic multivariate regression models with measurement error

In this paper, we develop modified versions of the likelihood ratio test for multivariate heteroskedastic errors-in-variables regression models. The error terms are allowed to follow a multivariate distribution in the elliptical class of distributions, which has the normal distribution as a special case. We derive the Skovgaard-adjusted likelihood ratio statistics, which follow a chi-squared distribution with a high degree of accuracy. We conduct a simulation study and show that the proposed tests display superior finite sample behaviour as compared to the standard likelihood ratio test. We illustrate the usefulness of our results in applied settings using a data set from the WHO MONICA Project on cardiovascular disease.     

Modern likelihood inference for the maximum/minimum of a bivariate normal vector

ABSTRACT

We consider the use of modern likelihood asymptotics in the construction of confidence intervals for the parameter which determines the skewness of the distribution of the maximum/minimum of an exchangeable bivariate normal random vector. Simulation studies were conducted to investigate the accuracy of the proposed methods and to compare them to available alternatives. Accuracy is evaluated in terms of both coverage probability and expected length of the interval. We furthermore illustrate the suitability of our proposals by means of two data sets, consisting of, respectively, measurements taken on the brains of 10 mono-zygotic twins and measurements of mineral content of bones in the dominant and non-dominant arms for 25 elderly women.     

Estimating the population proportion in modified ranked set sampling methods

In this paper, proportion estimators and associated variance estimators are proposed for a binary variable with a concomitant variable based on modified ranked set sampling methods, which are extreme ranked set sampling (ERSS), median ranked set sampling (MRSS), percentile ranked set sampling (Per-RSS) and L ranked set sampling (LRSS) methods. The Monte Carlo simulation study is performed to compare the performance of the estimators based on bias, mean squared error, and relative efficiency for different levels of correlation coefficient, set and cycle sizes under normal and log-normal distributions. Moreover, the study is supported with real data application.     

基于修正UTAUT模型的农信社手机银行使用行为研究——以福建省农户调查数据为例

基于UTAUT模型,引入感知风险、替代软件等2个变量进行修正,构建农信社手机银行使用行为影响因素研究模型,并运用结构方程模型、Bootstrap中介检验、多群组分析等方法对福建省农户调查数据进行实证分析。研究发现:(1)感知易用性显著正向影响农信社手机银行使用意愿;感知风险和替代软件显著负向影响农信社手机银行使用意愿;社会影响对农信社手机银行使用意愿影响不显著。(2)便利条件和使用意愿显著正向影响农信社手机银行使用行为;农信社手机银行使用行为影响因素由大到小依次为便利条件、替代软件、感知风险、感知易用性。(3)教育在感知易用性对农信社手机银行使用意愿影响中具有调节作用。据此提出,应进一步增强操作的便利性以优化业务办理效率,增强信息的安全性以降低软件使用风险,增强软件的特色性以降低软件可替代性,增强软件的易用性以优化便捷使用体验,从而优化农村金融服务供给,助推农村经济发展。     

Modified maximum likelihood estimator under the Jones and Faddy's skew t-error distribution for censored regression model

It is well-known that classical Tobit estimator of the parameters of the censored regression (CR) model is inefficient in case of non-normal error terms. In this paper, we propose to use the modified maximum likelihood (MML) estimator under the Jones and Faddy''s skew t-error distribution, which covers a wide range of skew and symmetric distributions, for the CR model. The MML estimators, providing an alternative to the Tobit estimator, are explicitly expressed and they are asymptotically equivalent to the maximum likelihood estimator. A simulation study is conducted to compare the efficiencies of the MML estimators with the classical estimators such as the ordinary least squares, Tobit, censored least absolute deviations and symmetrically trimmed least squares estimators. The results of the simulation study show that the MML estimators work well among the others with respect to the root mean square error criterion for the CR model. A real life example is also provided to show the suitability of the MML methodology.