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81.
This paper considers estimation and prediction in the Aalen additive hazards model in the case where the covariate vector is high-dimensional such as gene expression measurements. Some form of dimension reduction of the covariate space is needed to obtain useful statistical analyses. We study the partial least squares regression method. It turns out that it is naturally adapted to this setting via the so-called Krylov sequence. The resulting PLS estimator is shown to be consistent provided that the number of terms included is taken to be equal to the number of relevant components in the regression model. A standard PLS algorithm can also be constructed, but it turns out that the resulting predictor can only be related to the original covariates via time-dependent coefficients. The methods are applied to a breast cancer data set with gene expression recordings and to the well known primary biliary cirrhosis clinical data.  相似文献   
82.
新时期网络参政对中国民主政治发展促进作用将更加明显,是有中国特色民主政治发展的重要内容之一。网络参政的作用已经引起了党和国家领导人的重视,地方党和政府的负责人也逐渐注意到网络参政的实际意义,其作用主要体现在:促进参与式民主的发展;促进传统集权等级制权力结构的转换;促进社会平等;促进政治、政府公开的发展;促进选民与人大代表的沟通;促进公民政治社会化的加强。网络参政还是把双刃剑,应该加强规范和管理。  相似文献   
83.
Most studies of quality improvement deal with ordered categorical data from industrial experiments. Accounting for the ordering of such data plays an important role in effectively determining the optimal factor level of combination. This paper utilizes the correspondence analysis to develop a procedure to improve the ordered categorical response in a multifactor state system based on Taguchi's statistic. Users may find the proposed procedure in this paper to be attractive because we suggest a simple and also popular statistical tool for graphically identifying the really important factors and determining the levels to improve process quality. A case study for optimizing the polysilicon deposition process in a very large-scale integrated circuit is provided to demonstrate the effectiveness of the proposed procedure.  相似文献   
84.
Huber's estimator has had a long lasting impact, particularly on robust statistics. It is well known that under certain conditions, Huber's estimator is asymptotically minimax. A moderate generalization in rederiving Huber's estimator shows that Huber's estimator is not the only choice. We develop an alternative asymptotic minimax estimator and name it regression with stochastically bounded noise (RSBN). Simulations demonstrate that RSBN is slightly better in performance, although it is unclear how to justify such an improvement theoretically. We propose two numerical solutions: an iterative numerical solution, which is extremely easy to implement and is based on the proximal point method; and a solution by applying state-of-the-art nonlinear optimization software packages, e.g., SNOPT. Contribution: the generalization of the variational approach is interesting and should be useful in deriving other asymptotic minimax estimators in other problems.  相似文献   
85.
It is often the case that high-dimensional data consist of only a few informative components. Standard statistical modeling and estimation in such a situation is prone to inaccuracies due to overfitting, unless regularization methods are practiced. In the context of classification, we propose a class of regularization methods through shrinkage estimators. The shrinkage is based on variable selection coupled with conditional maximum likelihood. Using Stein's unbiased estimator of the risk, we derive an estimator for the optimal shrinkage method within a certain class. A comparison of the optimal shrinkage methods in a classification context, with the optimal shrinkage method when estimating a mean vector under a squared loss, is given. The latter problem is extensively studied, but it seems that the results of those studies are not completely relevant for classification. We demonstrate and examine our method on simulated data and compare it to feature annealed independence rule and Fisher's rule.  相似文献   
86.
大凡读过高中的人,都知道佛莱铭左手和右手定则,这种左、右定则很容易记错,有时要将手扭歪才能判定其方向,很难运用.为了方便学生记忆及方便判定方向,设法设计出一种新的右手定则,可以同时判定磁场对电流的作用力及磁场中导线所产生的感生电流的方向,显然这种右手定则是一个创新.  相似文献   
87.
Since the early 1970s the importance of mothers’ socioeconomic characteristics on their children’s educational and occupational attainment has been acknowledged. However, it is not clear if fathers’ characteristics have a stronger influence because men usually have stronger attachments to the labour market, or alternatively mothers’ characteristics are more important because of their greater role in children’s socialization. This study addresses this question by comparing the influence of father’s and mother’s education and occupation on student performance in literacy and numeracy using data from 30 countries. The impact of mother’s education is usually greater or comparable to that of father’s education. In contrast, substantially stronger effects for mother’s occupational status compared to father’s were rare. In most countries the impact of mother’s socioeconomic characteristics (education plus occupation) on student performance is comparable to that for father’s. Of the four indicators of socioeconomic background, father’s occupational status and mother’s educational attainment tend to have stronger effects, although many countries do not conform to this pattern. There are indications that the relative importance of mother’s characteristics have increased over time.
Gary Neil MarksEmail:
  相似文献   
88.
Media coverage of the death of Baby P revived national concerns about the standard of child safeguarding practice in England following the implementation of widespread structural changes in response to the Victoria Climbié Inquiry chaired by Lord Laming in 2003. This paper discusses the recommendations of Lord Laming's recent Progress Report. It questions whether the scale of the challenge in improving child protection is fully recognised and considers briefly the culture of social care in the UK and the barriers to effective reform. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
89.
Children living in foster care are an especially vulnerable population who often come to the attention of Medicaid mental health providers. These children experience a high incidence of emotional and behavioral disorders and may have specialized treatment needs related to their living arrangement status. This study assessed whether Children’s Psychosocial Rehabilitation could effectively treat youth with severe emotional and behavioral disorders who live in foster care. Analysis of data from an open trial of 218 clinically-impaired youth, aged 3–18 years, revealed no reliable differences in treatment outcome between foster versus non-foster children, with a trend toward more favorable outcomes for foster youth. Findings justify further study of the effectiveness of this Medicaid-funded service for the treatment of youth in care.  相似文献   
90.
This paper sets out the results of a Spanish study of the experience and meaning of work among disabled women of two generations, with three types of disability (physical, visual and hearing). Performing a socially recognised activity such as a job is a source of emotional welfare and self‐esteem. Moreover, it confers a certain social status. For the participants in this study the kind of work involved, whether productive, paid and ‘extra‐domestic’ or ‘reproductive’, unpaid and done at home, acquires different meanings, since for disabled women, sexist stereotypes – already more or less accentuated in the culture – social attitudes towards disability and personal factors introduce relevant differences, while leading to conflicts and dilemmas that these women have to solve. At any rate, their sense of responsibility in performing all types of work should be emphasised as evidence of their sense of independence and personal competence, forming a keystone in their construction of a sense of identity and social integration.  相似文献   
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