融合特征情感和产品参数的客户感知偏好模型

在线评论作为一种公开、可获取的信息资源,蕴含了关于产品质量的各种有价值的信息,对这些信息的分析与挖掘有助于企业了解客户的需求和偏好。目前,基于在线评论的客户偏好模型考虑了特征观点和评论数量,忽视了产品参数对消费者购买决策的影响。因此,本文提出了一种融合特征情感和产品参数的客户感知偏好模型。首先,利用在线评论提取客户讨论的产品特征,并识别产品特征的情感极性,从而进一步计算特征正负面情感得分,生成产品的特征情感。然后,结合企业定义的产品参数,构建特征情感和产品参数融合作用对产品销量影响的计量经济模型,分析客户对产品的感知偏好。最后,为验证模型的有效性,获取了汽车之家网站的39款汽车产品(SUV车型)的评论文本,并持续8个月的销量跟踪。研究结果显示本文提出的模型比信息增益和TF-IDF方法能够更加准确地获取客户的感知偏好。此外,研究结果解释了特征情感和产品参数与产品销量的关联关系,为企业的市场营销和产品设计决策提供了理论基础。     

A Floor,Not a Ceiling

Abstract

With the identification of twenty-six standards, this article argues that the child custody evaluation field has defined a set of minimum practice standards that go beyond the aspirational goals of existing “guidelines” and “parameters.7rdquo; These twenty-six standards constitute a floor, but not a ceiling, for conducting child custody evaluations (CCEs).     

Health Care Rationing Affecting Older Persons

Abstract

Health care resources are finite and, therefore, need to be rationed among potential users. Over the past decade and a half in the United States, a variety of explicit, official rationing schemes have been proposed, including some in which chronological age would play a significant role. For ethical and political reasons, it is very unlikely that any age-based rationing schemes will be adopted explicitly and officially. However, various de facto forms of health care rationing are occurring at present. This article outlines the implications of payer behavior, physician practice patterns, the development of evidence-based clinical practice parameters or guidelines, and reliance on consumer choice of health plans as unofficial and generally unacknowledged mechanisms of health care rationing that may exert an important impact on the accessibility of health services for older persons.     

浅论人体环节参数与专项化个性化的现代体育训练

体育与科技的联姻是体育运动发展的趋势,文章认为通过对生物力学分析中所采用的几种人体环节参数的研究,可得出对我国运动员进行动作分析时最适合采用的人体环节参数,为专项化、个性化的现代训练提供定量的依据。     

虚拟仪器实现污水参数实时在线监测

介绍了利用美国NI公司的Lab VIEW5．0开发多参数污水在线监测系统的过程，讨论了设计中的关键技术。     

Efficiency of projected score methods in rectangular array asymptotics

Summary. The paper considers a rectangular array asymptotic embedding for multistratum data sets, in which both the number of strata and the number of within-stratum replications increase, and at the same rate. It is shown that under this embedding the maximum likelihood estimator is consistent but not efficient owing to a non-zero mean in its asymptotic normal distribution. By using a projection operator on the score function, an adjusted maximum likelihood estimator can be obtained that is asymptotically unbiased and has a variance that attains the Cramér–Rao lower bound. The adjusted maximum likelihood estimator can be viewed as an approximation to the conditional maximum likelihood estimator.     

Bayesian classification of tumours by using gene expression data

Summary.  Precise classification of tumours is critical for the diagnosis and treatment of cancer. Diagnostic pathology has traditionally relied on macroscopic and microscopic histology and tumour morphology as the basis for the classification of tumours. Current classification frameworks, however, cannot discriminate between tumours with similar histopathologic features, which vary in clinical course and in response to treatment. In recent years, there has been a move towards the use of complementary deoxyribonucleic acid microarrays for the classi-fication of tumours. These high throughput assays provide relative messenger ribonucleic acid expression measurements simultaneously for thousands of genes. A key statistical task is to perform classification via different expression patterns. Gene expression profiles may offer more information than classical morphology and may provide an alternative to classical tumour diagnosis schemes. The paper considers several Bayesian classification methods based on reproducing kernel Hilbert spaces for the analysis of microarray data. We consider the logistic likelihood as well as likelihoods related to support vector machine models. It is shown through simulation and examples that support vector machine models with multiple shrinkage parameters produce fewer misclassification errors than several existing classical methods as well as Bayesian methods based on the logistic likelihood or those involving only one shrinkage parameter.     

半导体制冷保温容器制冷性能的实验研究

研制一种主要用于血液保存的半导体制冷保温容器的制冷系统.通过对其不同工作电压、环境温度及外部散热等条件制冷性能的研究,找出了影响半导体制冷性能的主要因素.确定了该制冷保温容器在不同环境温度下的最佳工作电压为12 V、最佳工作电流为4.5~4.8 A.并认定存在最佳热端散热强度等.另外,通过实验得出了在不同环境温度下,工作在最佳工作参数条件时制冷器内部所能达到的最低温度.     

固相化学反应研究(Ⅶ) 反应截面移动法研究氯化镍与H_2DMG的固相配位反应

用反应截面移动法研究了氯化镍与H_2DMG的固相配位反应。首次提出了用反应截面移动法计算等温固相反应动力学参数的方法,推测了可能的反应机理。     

Comparing Several Regression Models with Unequal Variances

We consider the problem of comparing k regression models, when the variances are not assumed to be equal. For this problem, the classical F test can lead to misleading results, and there is no simple test which adequately controls the size when the sample sizes are small. For k = 2, the most widely used test is the “weighted F test,” also known as the “asymptotic Chow test.” But this test does not work well for small samples, and various modifications have been proposed in the literature. For k > 2, few tests are available and only the parametric-bootstrap (PB) test of Tian et al. (2009) Tian, L., Ma, C., Vexler, A. (2009). A parametric bootstrap test for comparing heteroscedastic regression models. Communications in Statistics—Simulation and Computation, 38, 1026–1036.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar] controls the size fairly adequately. In this article, we propose three fairly simple F tests which can easily be applied in the general case, k ? 2, and avoid the complications of the PB test. Our simulations indicate that these tests have satisfactory performance. Also, our simulations confirm that the power properties of our proposed tests are similar to the PB test. Therefore, our proposed tests provide simple alternatives to the PB test, which can easily be used by practitioners who may not be familiar with the PB.