Smoothing parameter selection in nonparametric regression using an improved Akaike information criterion

Many different methods have been proposed to construct nonparametric estimates of a smooth regression function, including local polynomial, (convolution) kernel and smoothing spline estimators. Each of these estimators uses a smoothing parameter to control the amount of smoothing performed on a given data set. In this paper an improved version of a criterion based on the Akaike information criterion (AIC), termed AIC_C, is derived and examined as a way to choose the smoothing parameter. Unlike plug-in methods, AIC_C can be used to choose smoothing parameters for any linear smoother, including local quadratic and smoothing spline estimators. The use of AIC_C avoids the large variability and tendency to undersmooth (compared with the actual minimizer of average squared error) seen when other 'classical' approaches (such as generalized cross-validation (GCV) or the AIC) are used to choose the smoothing parameter. Monte Carlo simulations demonstrate that the AIC_C-based smoothing parameter is competitive with a plug-in method (assuming that one exists) when the plug-in method works well but also performs well when the plug-in approach fails or is unavailable.     

Theory & Methods: Krige,Smooth, Both or Neither?

Both kriging and non-parametric regression smoothing can model a non-stationary regression function with spatially correlated errors. However comparisons have mainly been based on ordinary kriging and smoothing with uncorrelated errors. Ordinary kriging attributes smoothness of the response to spatial autocorrelation whereas non-parametric regression attributes trends to a smooth regression function. For spatial processes it is reasonable to suppose that the response is due to both trend and autocorrelation. This paper reviews methodology for non-parametric regression with autocorrelated errors which is a natural compromise between the two methods. Re-analysis of the one-dimensional stationary spatial data of Laslett (1994) and a clearly non-stationary time series demonstrates the rather surprising result that for these data, ordinary kriging outperforms more computationally intensive models including both universal kriging and correlated splines for spatial prediction. For estimating the regression function, non-parametric regression provides adaptive estimation, but the autocorrelation must be accounted for in selecting the smoothing parameter.     

现代远程英语教学之我见

文章介绍了现代远程英语教育的理论基础，分析了现代远程英语教育的主要特征，提出了教师要成为意义建构的促进者和协作者、英语学习进程的组织者和指导者、英语学习资源的设计者和开发者，介绍了现代远程英语教学过程的设计。     

政治道德：执政党执政理念的伦理基础

政治道德是执政理念的价值基础，对“为谁执政、靠谁执政和如何执政”这三大执政理念提供道德支持。随着现代民主政治的发展，执政权力来源于并服务于公民的观念日益深入人心；公共权力只有充分履行社会管理职能，并选择科学的、民主的、法治的执政方式，才能获得权力运作的合理性基础。因此，在政党政治中，执政党只有以执政为民的政治道德统摄执政理念才能得到广泛的社会认同。     

太极拳诞生的地域文化背景

理清太极拳诞生的地域文化背景和地域文化内涵;以资料分析和历史史证相结合的手段,阐述太极拳诞生的地域文化背景;太极拳诞生于焦作地区,焦作地区厚重的地域文化乃是太极拳诞生的文化基础;焦作地区武学传统悠久,武术文化、道教文化源远流长,为太极拳的诞生营造了浓厚的文化氛围和理论基础。     

中国共产党农业政策的历史演变及现实思考——以1949—1978年为例

全面考察新中国农业发展的实践，理性梳理和阐释中国共产党的农业政策，总结其经验和教训，重要的是把握农业在国民经济中基础地位，高度重视农业经济的发展，遵循规律，积极推进农业现代化建设。     

Generalized Sobol sensitivity indices for dependent variables: numerical methods

The hierarchically orthogonal functional decomposition of any measurable function η of a random vector X=(X₁,?…?, X_p) consists in decomposing η(X) into a sum of increasing dimension functions depending only on a subvector of X. Even when X₁,?…?, X_p are assumed to be dependent, this decomposition is unique if the components are hierarchically orthogonal. That is, two of the components are orthogonal whenever all the variables involved in one of the summands are a subset of the variables involved in the other. Setting Y=η(X), this decomposition leads to the definition of generalized sensitivity indices able to quantify the uncertainty of Y due to each dependent input in X [Chastaing G, Gamboa F, Prieur C. Generalized Hoeffding–Sobol decomposition for dependent variables – application to sensitivity analysis. Electron J Statist. 2012;6:2420–2448]. In this paper, a numerical method is developed to identify the component functions of the decomposition using the hierarchical orthogonality property. Furthermore, the asymptotic properties of the components estimation is studied, as well as the numerical estimation of the generalized sensitivity indices of a toy model. Lastly, the method is applied to a model arising from a real-world problem.     

存在句的认知理据探讨

本文指出人们的视觉感知,心理感知,思维次序及认知经济原则是存在句结构生成的认知理据,并从认知角度对存在句进行历时溯因,对生成语言学在探讨这一问题时的局限性有新的见解。     

执政能力与新时期的人民民主发展

中国共产党的执政能力与人民民主发展相互促进,互相影响。改革开放新时期,中国共产党驾驭社会主义经济能力的提高,最终促成了人民民主建设物质基础的初步奠定;发展社会主义民主政治能力的不断增强,直接推动了人民民主建设制度保障的有效确立;发展社会主义先进文化能力的提高,有力指导了人民民主建设所需文化基础的初步形成。新世纪、新阶段,党要不断适应新要求,在实践中提高执政能力,将会推动人民民主建设更好地向前发展。     

“公司法人人格否认”概念正名及公司法人人格否认制度的思考

在我国<公司法>修改的立法背景下,通过考察公司法人人格否认制度的法理基础和特征,解析传统公司法人人格否认制度在概念表述上的困境,提出符合公司法人人格否认制度实质含义的科学表述"无视公司法人人格制度"或者"股东有限责任否认制度",并提出在我国设置公司法人否认制度的合理化建议.