Bias of factor loadings from questionnaire data with imputed scores

This study investigated the bias of factor loadings obtained from incomplete questionnaire data with imputed scores. Three models were used to generate discrete ordered rating scale data typical of questionnaires, also known as Likert data. These methods were the multidimensional polytomous latent trait model, a normal ogive item response theory model, and the discretized normal model. Incomplete data due to nonresponse were simulated using either missing completely at random or not missing at random mechanisms. Subsequently, for each incomplete data matrix, four imputation methods were applied for imputing item scores. Based on a completely crossed six-factor design, it was concluded that in general, bias was small for all data simulation methods and all imputation methods, and under all nonresponse mechanisms. Imputation method, two-way-plus-error, had the smallest bias in the factor loadings. Bias based on the discretized normal model was greater than that based on the other two models.     

基于灰关联分析的大学生成绩影响因素研究——以河南工业大学为例

通过对河南工业大学在校大学生的学习情况进行抽样问卷调查，利用灰关联分析对调查结果进行了研究，分析了影响学生学习成绩的主要因素，并给出了有导向性的指导。     

论社会需求是翻译选择的决定因素

本文从翻译选择的三个方面——文本内容、翻译方法、意识形态之选择——论证了只有社会需求才是译者多维选择的依据。这与胡庚申教授的翻译生态学理论并不矛盾。翻译生态学认为,翻译就是以译者为中心的多维选择与适应。本文认为,只有社会需求才是译者多维选择的决定因素,只有依据社会需求作出的选择,才能适应和促进社会发展,译作才能被社会接受。     

Planning sequential constant-stress accelerated life tests with stepwise loaded auxiliary acceleration factor

This article presents a design approach for sequential constant-stress accelerated life tests (ALT) with an auxiliary acceleration factor (AAF). The use of an AAF, if it exists, is to further amplify the failure probability of highly reliability testing items at low stress levels while maintaining an acceptable degree of extrapolation for reliability inference. Based on a Bayesian design criterion, the optimal plan optimizes the sample allocation, stress combination, as well as the loading profile of the AAF. In particular, a step-stress loading profile based on an appropriate cumulative exposure (CE) model is chosen for the AAF such that the initial auxiliary stress will not be too harsh. A case study, providing the motivation and practical importance of our study, is presented to illustrate the proposed planning approach.     

Estimation of the basic reproduction number for infectious diseases from age-stratified serological survey data

The basic reproduction number of an infection, R ₀, is the average number of secondary infections generated by a single typical infective individual in a totally susceptible population. It is directly related to the effort required to eliminate infection. We consider statistical methods for estimating R ₀ from age-stratified serological survey data. The main difficulty is indeterminacy, since the contacts between individuals of different ages are not observed. We show that, given an estimate of the average age-specific hazard of infection, a particular leading left eigenfunction is required to specify R ₀. We review existing methods of estimation in the light of this indeterminacy. We suggest using data from several infections transmitted via the same route, and we propose that the choice of model be guided by a criterion based on similarity of their contact functions. This approach also allows model uncertainty to be taken into account. If one infection induces no lasting immunity, we show that the only additional assumption required to estimate R ₀ is that the contact function is symmetric. When matched data on two or more infections transmitted by the same route are available, the methods may be extended to incorporate the effect of individual heterogeneity. The approach can also be applied in partially vaccinated populations and to populations comprising loosely linked communities. The methods are illustrated with data on hepatitis A, mumps, rubella, parvovirus, Haemophilus influenzae type b and measles infection.     

时谐偶极子在介质球头模型中的电位分布

考虑到脑电源的时谐性和头的电容效应,在电准静态近似下,建立了时谐等效电流偶极子模型;给出了其在均匀无限介质中和均匀介质球中的电位表达式;并正向计算了脑电源在非均匀各向同性三层同心介质球壳中的电位分布。最后讨论了时谐性和电容率对电位分布的影响。理论计算结果表明时谐性和电容率对电位分布确实有影响。     

西部城市经济竞争力分析

经济竞争力是构成城市竞争力的最主要因素之一。不断增强的城市经济竞争力是实现西部经济社会可持续发展的关键。构建了评估城市经济竞争力的指标体系；采用因子分析法对西部十二个省会城市的经济竞争力进行了评价，并将其分为三类；最后提出了增强西部城市经济竞争力的政策建议。     

引入制度和产业结构因素下的经济增长实证研究

本文在分析我国经济增长要素时,除选取传统的资本投入、劳动因素和人力资本作为解释变量外,还引入了制度因素和产业结构变量,通过建立变量间的回归模型并进行Granger因果检验和对变量的序列相关性及平稳性进行检验的基础上,建立了具有良好统计性质的协整与误差修正模型,较好地解释了影响我国经济增长的主要因素。     

广西县域第三产业与旅游经济发展分析

通过因子分析和层次分析法分别研究了广西县域第三产业发展状况和各县旅游业发展条件,最后用多元回归法分析了第三产业其他部门水平的提高对旅游业发展的影响,结果显示,在旅游品牌效应较强的县域,旅游业的发展主要依托旅游资源条件;而在旅游品牌效应较弱的县域,旅游业的发展主要依托第三产业的其他部门。     

On the Use of Hierarchical Probabilistic Models for Characterizing and Managing Uncertainty in Risk/Safety Assessment

A general probabilistically-based approach is proposed for both cancer and noncancer risk/safety assessments. The familiar framework of the original ADI/RfD formulation is used, substituting in the numerator a benchmark dose derived from a hierarchical pharmacokinetic/pharmacodynamic model and in the denominator a unitary uncertainty factor derived from a hierarchical animal/average human/sensitive human model. The empirical probability distributions of the numerator and denominator can be combined to produce an empirical human-equivalent distribution for an animal-derived benchmark dose in external-exposure units.