Robustness of a Class of Partial Diallel Cross Designs to the Unavailability of a Complete Block of Observations

Complete and partial diallel cross designs are examined as to their construction and robustness against the loss of a block of observations. A simple generalized inverse is found for the information matrix of the line effects, which allows evaluation of expressions for the variances of the line-effect differences with and without the missing block. A-efficiencies, based on average variances of the elementary contrasts of the line-effects, suggest that these designs are fairly robust. The loss of efficiency is generally less than 10%, but it is shown that specific comparisons might suffer a loss of efficiency of as much as 40%.     

Attracting Micro‐Enterprises To Learning

Micro‐enterprises, i.e. firms with less than 10 employees, are traditionally the hardest to engage in learning; they are also least likely to participate in such measures as business advice and guidance provision and initiatives to support information communication technology (ICT) adoption. Through a community‐based initiative initially targeting parents (unemployed or employed) to participate in ICT, 30 micro‐enterprises were attracted to learning for the first time. These companies had carefully avoided similar initiatives taking place locally, which emphasized business success and growth; they had only participated in this ICT skills training because of their children. The paper takes a case study approach to evaluate the reasons for participation, explores barriers and implications for those organizing similar activities, and calls for a more holistic view of owners and managers of small firms as fathers, mothers, etc. rather than just as ‘entrepreneurs’.     

“数字鸿沟”：当代社会阶层分析的新视角*

当代社会，随着信息技术的发展以及信息重要性的增强，以互联网等为基础的电子信息网络已经浸透于社会的各个领域之中，在产业、经济和社会中生成着一种新的信息场域，影响着人们的社会生活。本文从社会阶层的研究视角出发，透过“现代——后现代”的二维分析模式对信息及信息技术带来的“数字鸿沟”现象进行理论上的阐释，对其究竟是实现着“阶层化”还是“去阶层化”进行探讨，并对信息化高度发达的日本社会进行了“数字鸿沟”的实证分析。可以看出：信息、信息技术已经成为一种新的变量，并与社会阶层之间产生着密切的关系，重塑着社会阶层化机制。     

海报设计的竞争优势及发展趋向

海报设计在长达一个多世纪的发展过程中,经历了不断的发展和演变,形成了独特的风格和特点。文章主要分析了海报在当代社会的存在状况以及竞争优势;论述了海报设计作为一种设计艺术形态,在全球一体化的社会环境中蕴涵着个人化、艺术化以及多元化的发展趋势。     

Profile information matrix for nonlinear transformation models

For semiparametric models, interval estimation and hypothesis testing based on the information matrix for the full model is a challenge because of potentially unlimited dimension. Use of the profile information matrix for a small set of parameters of interest is an appealing alternative. Existing approaches for the estimation of the profile information matrix are either subject to the curse of dimensionality, or are ad-hoc and approximate and can be unstable and numerically inefficient. We propose a numerically stable and efficient algorithm that delivers an exact observed profile information matrix for regression coefficients for the class of Nonlinear Transformation Models [A. Tsodikov (2003) J R Statist Soc Ser B 65:759-774]. The algorithm deals with the curse of dimensionality and requires neither large matrix inverses nor explicit expressions for the profile surface.     

一种基于加权F-范数的半正定矩阵的逼近方法

正定性是许多金融预测模型的重要假设前提，然而从实际样本中得到的相关系数矩阵并不能保证其正定性。为此在介绍如何根据样本设定相关系数矩阵以及范数逼近原理的基础上，如何根据该原理找到与之最接近的相关系数矩阵，即最接近的单位对角半正定对称矩阵。通过实证，验证了其方法的有效性。     

Error rates in classification consisting of discrete and continuous variables in the presence of covariates

We consider classifying an object based on mixed continuous and discrete variables between two populations. Mixed discrete and continuous covariates with identical means in both populations are amongst the variables. Under the location model with homogeneous location specific conditional dispersion matrices for both populations, the Bayes rule is given. Classification is implemented by a plug-in version of the Bayes rule with full covariate adjustment. An asymptotic expansion of the overall expected error of the procedure is derived. Our findings generalize several classical results.     

Vector random fields with compactly supported covariance matrix functions

The objective of this paper is to construct covariance matrix functions whose entries are compactly supported, and to use them as building blocks to formulate other covariance matrix functions for second-order vector stochastic processes or random fields. In terms of the scale mixture of compactly supported covariance matrix functions, we derive a class of second-order vector stochastic processes on the real line whose direct and cross covariance functions are of Pólya type. Then some second-order vector random fields in R^d${\mathbb{R}}^d$ whose direct and cross covariance functions are compactly supported are constructed by using a convolution approach and a mixture approach.     

Two-level minimum aberration designs in N =2 (mod 4) runs

For two-level factorials, we consider designs in N=2 (mod 4) runs as obtained by adding two runs, with a certain coincidence pattern, to an orthogonal array of strength two. These designs are known to be optimal main effect plans in a very broad sense in the absence of interactions. Among them, we explore the ones having minimum aberration, with a view to ensuring maximum model robustness even when interactions are possibly present. This is done by sequentially minimizing a measure of the bias caused by interactions of successively higher orders.