Third-Order Asymptotic Distributions of Classic Test Statistics for One-Parameter Exponential Family Models

ABSTRACT

In this article we derive third-order asymptotic expansions for the non null distribution functions of four classic statistics under a sequence of local alternatives in one-parameter exponential family models. Our results are quite general and cover a wide range of important distributions.     

Variance bounds for estimators in autoregressive models with constraints

We consider nonlinear and heteroscedastic autoregressive models whose residuals are martingale increments with conditional distributions that fulfil certain constraints. We treat two classes of constraints: residuals depending on the past through some function of the past observations only, and residuals that are invariant under some finite group of transformations. We determine the efficient influence function for estimators of the autoregressive parameter in such models, calculate variance bounds, discuss information gains, and suggest how to construct efficient estimators. Without constraints, efficient estimators can be given by weighted least squares estimators. With the constraints considered here, efficient estimators are obtained differently, as one-step improvements of some initial estimator, similarly as in autoregressive models with independent increments.     

ON SOME OPTIMALITY PROPERTIES OF FISHER-RAO SCORE FUNCTION IN TESTING AND ESTIMATION

The score function is associated with some optimality features in statistical inference. This review article looks on the central role of the score in testing and estimation. The maximization of the power in testing and the quest for efficiency in estimation lead to score as a guiding principle. In hypothesis testing, the locally most powerful test statistic is the score test or a transformation of it. In estimation, the optimal estimating function is the score. The same link can be made in the case of nuisance parameters: the optimal test function should have maximum correlation with the score of the parameter of primary interest. We complement this result by showing that the same criterion should be satisfied in the estimation problem as well.     

Research Design Meets Market Design: Using Centralized Assignment for Impact Evaluation

A growing number of school districts use centralized assignment mechanisms to allocate school seats in a manner that reflects student preferences and school priorities. Many of these assignment schemes use lotteries to ration seats when schools are oversubscribed. The resulting random assignment opens the door to credible quasi‐experimental research designs for the evaluation of school effectiveness. Yet the question of how best to separate the lottery‐generated randomization integral to such designs from non‐random preferences and priorities remains open. This paper develops easily‐implemented empirical strategies that fully exploit the random assignment embedded in a wide class of mechanisms, while also revealing why seats are randomized at one school but not another. We use these methods to evaluate charter schools in Denver, one of a growing number of districts that combine charter and traditional public schools in a unified assignment system. The resulting estimates show large achievement gains from charter school attendance. Our approach generates efficiency gains over ad hoc methods, such as those that focus on schools ranked first, while also identifying a more representative average causal effect. We also show how to use centralized assignment mechanisms to identify causal effects in models with multiple school sectors.     

网络游戏成瘾量表研究——事件相关脑电位辅助分析

在我国网络游戏产业发展迅猛,网民数量持续高速增长,但同时也出现了网游玩家沉迷于网络游戏中而产生心理依赖的成瘾症状.目前对网络成瘾的概念、界定指标和测量工具都存在较大争议,缺乏网络成瘾界定的系统研究.本研究在以往多种量表的基础上,采用事件相关脑电位方法,采用成瘾Stroop实验范式,找到了可以区分网络游戏成瘾者和正常网络使用者的客观电生理指标,验证了这个分类.通过对这群已经被验证了的两组被试的问卷测量,形成了"网络游戏成瘾量表",并依据测量结果,给出了推断被试是否成瘾的总分分界值.然后,采用重测信度方法,验证了量表的稳定性和可靠性.最后,用测量预留的成瘾被试,验证了"网络游戏成瘾量表"的有效性.     

Noninformative priors for the normal variance ratio

In this paper, we consider noninformative priors for the ratio of variances in two normal populations. We develop first and second order matching priors. We find that the second order matching prior matches alternative coverage probabilities up to the second order and is also a HPD matching prior. It turns out that among the reference priors, only one-at-a-time reference prior satisfies a second order matching criterion. Our simulation study indicates that the one-at-a-time reference prior performs better than other reference priors in terms of matching the target coverage probabilities in a frequentist sense. This work is supported by Korea Research Foundation Grant (KRF-2004-002-C00041).     

A Test to Detect Within-family Infectivity when the Whole Epidemic Process is Observed

An epidemic model for the spread of an infectious disease in a population of families is considered. The score test of the hypothesis that there is no higher infectivity between family members is constructed under the assumption that the epidemic process is observed continuously up to some time t . The score process is a martingale as a function of t and by letting the number of families tend to infinity, a central limit theorem for the process can be proved. The central limit theorem not only justifies a normal approximation of the test statistic—it also suggests a smaller variance estimator than expected.     

战略和价值导向的管理系统--综合计分卡

综合计分卡不仅仅是一种评估系统,更是一种基于战略和价值导向的管理系统.综合计分卡重点关注企业的财务、客户、内部经营过程、学习与成长等四个方面,强调财务目标与非财务目标的有机结合,强调财务目标和业绩驱动因素的内在联系,从而使企业战略转化为员工行动,保证企业战略实施,提高股东价值.本文主要通过分析综合计分卡与战略、价值的关系,分析综合计分卡四个方面及其内在联系,并结合国外综合计分卡的实践经验,探讨综合计分卡作为一种战略管理工具对企业业绩、战略实施、核心竞争力建立的有益作用,进而对中国企业实践综合计分卡问题进行研究.     

中国城镇居民10年消费结构变化实证研究

通过运用扩展线性支出系统模型(ELES)对城镇居民边际消费倾向和需求收入弹性进行实证研究，得出我国城镇居民满足吃、穿为主的生存型消费需求阶段已经结束，逐步向以发展型和享受型阶段过渡．同时预测恩格尔系数会继续下降，高层次消费项目将成为新的消费增长点．最后针对我国城镇居民消费结构变化提出政策性建议．     

一种快速有效提取浓密视差图的方法

采用边缘匹配和区域相关相结合的办法,用Gauss-Laplace算子首先对图像进行运算,提取图像的边缘像素,并根据一定约束条件匹配边缘像素,再将图像对视作对称,以相关值互为最大来确定其余点的匹配关系。用该方法处理经过良好校正的图像对,在VC 环境下可实现浓密视差图的快速提取。