Variable Selection in Joint Location and Scale Models of the Skew-t-Normal Distribution

Variable selection is an important issue in all regression analysis, and in this article, we investigate the simultaneous variable selection in joint location and scale models of the skew-t-normal distribution when the dataset under consideration involves heavy tail and asymmetric outcomes. We propose a unified penalized likelihood method which can simultaneously select significant variables in the location and scale models. Furthermore, the proposed variable selection method can simultaneously perform parameter estimation and variable selection in the location and scale models. With appropriate selection of the tuning parameters, we establish the consistency and the oracle property of the regularized estimators. These estimators are compared by simulation studies.     

A comparison of three methods of estimating the logistic regression coefficients

A Sampling experiment performed using data collected for a large clinical trial shows that the discriminant function estimates of the logistic regression coefficients for discrete variables may be severely biased. The simulations show that the mixed variable location model coefficient estimates have bias which is of the same magnitude as the bias in the coefficient estimates obtained using conditional maximum likelihood estimates but require about one-tenth of the computer time.     

Combining Univariate Tests for Multivariate Location Problem

In this article, three methods of combining dependent univariate tests are studied. The Bahadur approximate efficiencies are derived under the asymptotic normal assumption. These procedures are applied to the multivariate location problem and compared with two Hotelling-type tests. A Monte Carlo study indicates that in certain cases the powers of the combination methods are much better than Hotelling's T ² and other multivariate nonparametric tests.     

Robust location estimation with missing data

In a missing data setting, we have a sample in which a vector of explanatory variables ${\bf x}_i$ is observed for every subject i, while scalar responses $y_i$ are missing by happenstance on some individuals. In this work we propose robust estimators of the distribution of the responses assuming missing at random (MAR) data, under a semiparametric regression model. Our approach allows the consistent estimation of any weakly continuous functional of the response's distribution. In particular, strongly consistent estimators of any continuous location functional, such as the median, L‐functionals and M‐functionals, are proposed. A robust fit for the regression model combined with the robust properties of the location functional gives rise to a robust recipe for estimating the location parameter. Robustness is quantified through the breakdown point of the proposed procedure. The asymptotic distribution of the location estimators is also derived. The proofs of the theorems are presented in Supplementary Material available online. The Canadian Journal of Statistics 41: 111–132; 2013 © 2012 Statistical Society of Canada     

基于双层规划的反恐应急设施选址模型及算法

恐怖袭击常以人流密集地区的平民作为袭击目标，并存在突发性和随机性等特点，极易造成严重的袭击后果。通过反恐应急设施的合理布局可以缩短救援人员和物资的到达时间，从而减轻袭击后果。首先，对反恐应急设施选址问题进行描述，并将其构造为一类离散双层规划模型。其中，上层规划是关于政府选址的0-1规划问题，下层规划则是关于恐怖分子袭击目标选择的0-1规划问题。其次，结合模型和问题的特征设计算法，利用分支定界算法实现上层选址变量的隐枚举，同时通过下层问题的求解来确定上下界并判断是否满足分枝或剪枝的条件。最后，结合南疆地区的交通拓扑网络进行算例分析，结果证明有效的选址方案可以大大降低袭击损失。     

Facility Location with Dynamic Distance Functions

Facility location problems have always been studied with theassumption that the edge lengths in the network are static anddo not change over time. The underlying network could be used to model a city street networkfor emergency facility location/hospitals, or an electronic network for locating information centers. In any case, it is clear that due to trafficcongestion the traversal time on links changes with time. Very often, we have estimates as to how the edge lengths change over time, and our objective is to choose a set of locations (vertices) ascenters, such that at every time instant each vertex has a center close to it (clearly, the center close to a vertex may change over time). We also provide approximation algorithms as well as hardness results forthe K-center problem under this model. This is the first comprehensive study regarding approximation algorithmsfor facility location for good time-invariant solutions.     

A characterization of the dilation order and its applications

LetX andY be two random variables with finite expectationsE X andE Y, respectively. ThenX is said to be smaller thanY in the dilation order ifE[ϕ(X-E X)]≤E[ϕ(Y-E Y)] for any convex functionϕ for which the expectations exist. In this paper we obtain a new characterization of the dilation order. This characterization enables us to give new interpretations to the dilation order, and using them we identify conditions which imply the dilation order. A sample of applications of the new characterization is given. Partially supported by MURST 40% Program on Non-Linear Systems and Applications. Partially supported by “Gruppo Nazionale per l'Analisi Funzionale e sue Applicazioni”—CNR.     

洛阳方言的方位和时间后缀

洛阳方言中有而普通话没有的方位后缀有20个、普通话里有而洛阳方言中没有的方位后缀有4个、洛阳方言与普通话都有的方位后缀有7个（包含零形式后缀）;洛阳方言中有而普通话没有的时间后缀有7个、洛阳话和普通话里都有的时间后缀有6个（包含零形式后缀）。总体上讲,洛阳方言与普通话在方位和时间后缀的使用方面既有共性又有差别,差别大于共性。     

海南五指山苦丁茶黄酮含量测定的研究

通过测定海南五指山不同等级苦丁茶中黄酮的含量,并与国内其他地区的苦丁茶黄酮含量比较,发现五指山苦丁茶有较好的药用价值,具备良好的地域竞争优势和发展前景。     

湖北自贸试验区的制度创新:实践特征、理论内涵与政策启示

建设湖北自贸试验区是新发展阶段全面深化改革、扩大开放的系统性探索和战略实践,从动态演进论与制度变迁、制度经济学的交易成本论以及公共经济学的公共物品供需视角,对自贸试验区制度创新的理论逻辑与实践意义予以系统研究。研究发现,湖北自贸试验区围绕加快转变政府职能、深化投资领域改革、促进贸易转型升级、推动金融开放创新、创新驱动发展以及服务国家战略等方面展开了一系列制度创新实践,逐步形成由浅入深、由线下向线上线下协同发展、由共性领域向特色领域逐步延伸、从前项到末端统筹安排、借鉴与创新并举以及集中推广与自主运用相结合的改革创新发展路径。研究认为,推动湖北自贸试验区的制度创新,充分发挥其在破解地方深层次结构性发展矛盾和扩展增长赋能空间上的功能内涵,需要在顶层制度设计方面,加强与国内国际双循环新发展格局相互衔接,通过完善监管体系设计、提升行政服务效率来转变政府监管职能和健全市场监管,构建由法律法规、行政规章、规范性文件共同组成的、与国际规范兼容协调的法制框架和政策体系,统筹为国家试制度、出经验的全局性战略目标与谋求为地区经济发展注活力、添动力的局部性现实需求之间的激励导向; 在具体实施路径层面,持续优化开放平台、营商环境和加强口岸智慧功能建设,着力培育和强化大城市、大枢纽、大口岸、大平台、大产业以及一流的营商环境等,构建开放型经济新体制和多维量化评估指标体系,实现自贸试验区制度创新实践探索、经验成效审视验证、赋能社会经济发展以及长远建设规划目标的有机协调统一,助力湖北建设新时代内陆开放新高地。