Communities of Knowledge: Creating and Connecting Resource Metadata

A growing number of academic libraries and consortia are developing their own e-resource knowledge bases. The structure, format, and ultimate goals of their projects vary. If they are successful, these community-driven knowledge bases have the potential to make a positive impact on e-resource management and discovery. A situation analysis of the current state of affairs considers the problems these new communities of knowledge are attempting to solve, compares the scope and approaches of selected projects, suggests opportunities for connectivity across communities, and outlines challenges to their success. This article is the outgrowth of a 2013 North Carolina Serials Conference discussion.     

Weighted transformed hazard anova for censored and truncated data

In this paper ANOVA test procedures based on weighted transformations of the cumulative hazard are discussed. These procedures may be applied in situations where the observations are censored and/or truncated. Besides, the techniques examined are flexible thanks to the choice of different transformations and weight functions. The popular logrank test is used as a yardstick in the performance evaluation.     

Nonparametric methods in factorial designs

Summary In this paper, we summarize some recent developments in the analysis of nonparametric models where the classical models of ANOVA are generalized in such a way that not only the assumption of normality is relaxed but also the structure of the designs is introduced in a broader framework and also the concept of treatment effects is redefined. The continuity of the distribution functions is not assumed so that not only data from continuous distributions but also data with ties are included in this general setup. In designs with independent observations as well as in repeated measures designs, the hypotheses are formulated by means of the distribution functions. The main results are given in a unified form. Some applications to special designs are considered, where in simple designs, some well known statistics (such as the Kruskal-Wallis statistic and the χ²-statistic for dichotomous data) come out as special cases. The general framework presented here enables the nonparametric analysis of data with continuous distribution functions as well as arbitrary discrete data such as count data, ordered categorical and dichotomous data. Received: October 13, 1999; revised version: June 26, 2000     

Hitch-hiker's guide to genetic algorithms

Genetic algorithms are a set of algorithms with properties which enable them to efficiently search large solution spaces where conventional statistical methodology is inappropriate. They have been used to find effective control and design strategies in industry, for finding rules relating factors and outcomes in medicine and business, and for solving problems ranging from function optimization to identification of patterns in data. They work using ideas from biology, specifically from population genetics, and are appealing because of their robustness in the presence of noise and their ability to cope with highly non-linear, multimodal and multivariate problems. This paper reviews the current literature on genetic algorithms. It looks at ways of defining genetic algorithms for various problems, and examples are introduced to illustrate their application in different contexts. It summarizes the different aspects which have been, and continue to be, the focus of research, and areas requiring further invetigation are identified.     

基于大数据思维的统计学若干理论问题

本文基于大数据思维,对统计学若干理论问题进行了讨论。本文认为：在大数据背景下,统计学以数据为研究对象没有变,作为方法论科学的性质没有变,以探索真相为根本任务没有变;但是作为统计学研究对象的数据出现了四个新的动向,即数据内涵有新理解,数据结构与来源有新方式,数据不确定性有新表现,数据分析思路与技术有新要求;为此,需要重新理解和定义总体、个体与样本,标志与变量,可靠性与有效性这三组统计学中最基本也最重要的概念。最后论文指出,大数据为统计学发展提供了新的平台,需要我们从数据、方法和应用三个维度同时发力。     

社会核算矩阵编制中的数据衔接问题研究

由于数据来源不同,所以在编制社会核算矩阵时会出现大量数据不衔接的问题.目前国内外学者多数采用RAS、CE等方法进行平衡处理,而这些方法都属于纯数学线性调整和平衡方法,并没有考虑具体数据的现实经济意义.鉴此,设计一种“项目对应平衡法”,以矩阵表中元素的具体经济含义为依据,对所有不平衡项目进行逐项处理,以达到整个矩阵的总体平衡.同时采用这种平衡方法,实际编制了2007年中国社会核算矩阵.     

非等间隔动态面板数据模型：基于半差分的估计方法和应用

本文提出了非等间隔动态面板数据模型的估计方法,包括非线性最小二乘和最短距离估计法以及这两种估计方法的一步估计量,并且证明了这几个估计量的一致性和渐进正态性。我们使用数值模拟的方法验证了这些估计在有限样本中的估计精度,并且将这四种估计方法应用于实际的问题当中,最终得到了与以往的文献基本一致的估计结果。     

大数据应用的质量控制

数据作为重要的数据资源存在，不论是其内在蕴含的信息价值还是其已经成为人类社会所需数据有机组成的客观事实，都迫使我们去不断加强对大数据的应用。然而，由于大数据作为信息技术应用的副产品，其复杂性、不确定性和涌现性决定了我们应用大数据并非易事，存在着很多质量上的问题，除了具有传统数据所有的质量问题外，还包括一些独特的新问题。为了更好地应用大数据，本文对如何进行大数据应用的质量控制进行了初步的研究。主要内容包括以下三个方面：一是对什么是大数据质量、受哪些因素影响、可能存在哪些质量问题进行了探讨；二是从做好理论准备、建立质量控制方案、重视对小数据研究、加强大数据管理、加强大数据人才培养和加强大数据法制建设六个方面，提出了大数据应用的质量控制的基本想法；三是对大数据应用中需要引起注意的几个方面进行了讨论，并结合例子进行了阐释。     

价格数据缺失、失真与PPP测算偏差

基础数据质量问题对PPP测算结果的影响既需要有定性的客观认识,更需要量化的测算结果做依据。本文首先依据数据审核的基本逻辑将价格数据质量问题抽象为数据缺失和数据失真两种类型;其次借鉴对照实验方法,以CPD法为基础,通过对两类数据质量问题不同形式和程度的量化模拟,综合考察了两类数据质量问题影响下的CPD-PPP测算偏差特征与规律;最后综合模拟测度结果为ICP基础数据质量的控制与优化以及比较结果的量化评估与调整提出了意见与建议。     

Challenges and Opportunities for Statistics and Statistical Education: Looking Back,Looking Forward

The 175th anniversary of the ASA provides an opportunity to look back into the past and peer into the future. What led our forebears to found the association? What commonalities do we still see? What insights might we glean from their experiences and observations? I will use the anniversary as a chance to reflect on where we are now and where we are headed in terms of statistical education amidst the growth of data science. Statistics is the science of learning from data. By fostering more multivariable thinking, building data-related skills, and developing simulation-based problem solving, we can help to ensure that statisticians are fully engaged in data science and the analysis of the abundance of data now available to us.     

An augmented data scoring algorithm for maximum likelihood

The expectation-maximization (EM) method facilitates computation of max¬imum likelihood (ML) and maximum penalized likelihood (MPL) solutions. The procedure requires specification of unobservabie complete data which augment the measured or incomplete data. This specification defines a conditional expectation of the complete data log-likelihood function which is computed in the E-stcp. The EM algorithm is most effective when maximizing the iunction Q{0) denned in the F-stnp is easier than maximizing the likelihood function.

The Monte Carlo EM (MCEM) algorithm of Wei & Tanner (1990) was introduced for problems where computation of Q is difficult or intractable. However Monte Carlo can he computationally expensive, e.g. in signal processing applications involving large numbers of parameters. We provide another approach: a modification of thc standard EM algorithm avoiding computation of conditional expectations.     

Selection bias,investment decisions and treatment effect distributions

When making decisions regarding the investment and design for a Phase 3 programme in the development of a new drug, the results from preceding Phase 2 trials are an important source of information. However, only projects in which the Phase 2 results show promising treatment effects will typically be considered for a Phase 3 investment decision. This implies that, for those projects where Phase 3 is pursued, the underlying Phase 2 estimates are subject to selection bias. We will in this article investigate the nature of this selection bias based on a selection of distributions for the treatment effect. We illustrate some properties of Bayesian estimates, providing shrinkage of the Phase 2 estimate to counteract the selection bias. We further give some empirical guidance regarding the choice of prior distribution and comment on the consequences for decision-making in investment and planning for Phase 3 programmes.     

零膨胀计数数据函数型部分变系数模型

在实际数据分析中经常会遇到零膨胀计数数据作为响应变量与函数型随机变量和随机向量作为预测变量相关联。本文考虑函数型部分变系数零膨胀模型 (FPVCZIM),模型中无穷维的斜率函数用函数型主成分基逼近,系数函数用B-样条进行拟合。通过EM 算法得到估计量,讨论其理论性质,在一些正则条件下获得了斜率函数和系数函数估计量的收敛速度。有限样本的Monte Carlo 模拟研究和真实数据分析被用来解释本文提出的方法。     

Testing for lack of fit in inverse regression—with applications to biophotonic imaging

Summary.  We propose two test statistics for use in inverse regression problems Y = K θ + ɛ , where K is a given linear operator which cannot be continuously inverted. Thus, only noisy, indirect observations Y for the function θ are available. Both test statistics have a counterpart in classical hypothesis testing, where they are called the order selection test and the data-driven Neyman smooth test. We also introduce two model selection criteria which extend the classical Akaike information criterion and Bayes information criterion to inverse regression problems. In a simulation study we show that the inverse order selection and Neyman smooth tests outperform their direct counterparts in many cases. The theory is motivated by data arising in confocal fluorescence microscopy. Here, images are observed with blurring, modelled as convolution, and stochastic error at subsequent times. The aim is then to reduce the signal-to-noise ratio by averaging over the distinct images. In this context it is relevant to decide whether the images are still equal, or have changed by outside influences such as moving of the object table.     

Mixture models: building a parameter space

Despite the flexibility and popularity of mixture models, their associated parameter spaces are often difficult to represent due to fundamental identification problems. This paper looks at a novel way of representing such a space for general mixtures of exponential families, where the parameters are identifiable, interpretable, and, due to a tractable geometric structure, the space allows fast computational algorithms to be constructed.     

Integrated methodology for multiple systems estimation and record linkage using a missing data formulation

There are now three essentially separate literatures on the topics of multiple systems estimation, record linkage, and missing data. But in practice the three are intimately intertwined. For example, record linkage involving multiple data sources for human populations is often carried out with the expressed goal of developing a merged database for multiple system estimation (MSE). Similarly, one way to view both the record linkage and MSE problems is as ones involving the estimation of missing data. This presentation highlights the technical nature of these interrelationships and provides a preliminary effort at their integration.     

INFLUENCE FUNCTIONS IN FUNCTIONAL MEASUREMENT ERROR MODELS WITH REPLICATED DATA

We consider the construction and properties of influence functions in the context of functional measurement error models with replicated data. In these models estimates of the parameters can be affected both by the individual observations and the means of replicated observations. We show that influence function of the means of replicates on the estimate of regression coefficients can be only derived under the assumption that the variances of the errors are known, while one for the individual observations can be only derived simultaneously with their influence function on the estimators of the variances of the errors.     

城市基础设施建设国债投资分析——行业系列分析之三

城市基础设施是现代城市赖以生存和发展的基本条件,是为城市国民经济各部门、人民生活提供服务的载体。它包括：给水排水系统、污水处理、燃气系统、城市供热、市内道路桥梁隧道、公共交通、园林绿化、环境卫生、防洪防火防震设施等。城市基础设施的好坏直接影响到城市经...     

Semi-parametric hybrid empirical likelihood inference for two-sample comparison with censored data

Two-sample comparison problems are often encountered in practical projects and have widely been studied in literature. Owing to practical demands, the research for this topic under special settings such as a semiparametric framework have also attracted great attentions. Zhou and Liang (Biometrika 92:271–282, 2005) proposed an empirical likelihood-based semi-parametric inference for the comparison of treatment effects in a two-sample problem with censored data. However, their approach is actually a pseudo-empirical likelihood and the method may not be fully efficient. In this study, we develop a new empirical likelihood-based inference under more general framework by using the hazard formulation of censored data for two sample semi-parametric hybrid models. We demonstrate that our empirical likelihood statistic converges to a standard chi-squared distribution under the null hypothesis. We further illustrate the use of the proposed test by testing the ROC curve with censored data, among others. Numerical performance of the proposed method is also examined.     

The estimating function bootstrap

The authors propose a bootstrap procedure which estimates the distribution of an estimating function by resampling its terms using bootstrap techniques. Studentized versions of this so‐called estimating function (EF) bootstrap yield methods which are invariant under reparametrizations. This approach often has substantial advantage, both in computation and accuracy, over more traditional bootstrap methods and it applies to a wide class of practical problems where the data are independent but not necessarily identically distributed. The methods allow for simultaneous estimation of vector parameters and their components. The authors use simulations to compare the EF bootstrap with competing methods in several examples including the common means problem and nonlinear regression. They also prove symptotic results showing that the studentized EF bootstrap yields higher order approximations for the whole vector parameter in a wide class of problems.