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1.
This paper is concerned with inference about a function g that is identified by a conditional quantile restriction involving instrumental variables. The paper presents a test of the hypothesis that g belongs to a finite-dimensional parametric family against a nonparametric alternative. The test is not subject to the ill-posed inverse problem of nonparametric instrumental variable estimation. Under mild conditions, the test is consistent against any alternative model. In large samples, its power is arbitrarily close to 1 uniformly over a class of alternatives whose distance from the null hypothesis is proportional to n−1/2, where n is the sample size. Monte Carlo simulations illustrate the finite-sample performance of the test.  相似文献   

2.
Longitudinal methods have been widely used in biomedicine and epidemiology to study the patterns of time-varying variables, such as disease progression or trends of health status. Data sets of longitudinal studies usually involve repeatedly measured outcomes and covariates on a set of randomly chosen subjects over time. An important goal of statistical analyses is to evaluate the effects of the covariates, which may or may not depend on time, on the outcomes of interest. Because fully parametric models may be subject to model misspecification and completely unstructured nonparametric models may suffer from the drawbacks of "curse of dimensionality", the varying-coefficient models are a class of structural nonparametric models which are particularly useful in longitudinal analyses. In this article, we present several important nonparametric estimation and inference methods for this class of models, demonstrate the advantages, limitations and practical implementations of these methods in different longitudinal settings, and discuss some potential directions of further research in this area. Applications of these methods are illustrated through two epidemiological examples.  相似文献   

3.
Since the work of Little and Rubin (1987) not substantial advances in the analysisof explanatory regression models for incomplete data with missing not at randomhave been achieved, mainly due to the difficulty of verifying the randomness ofthe unknown data. In practice, the analysis of nonrandom missing data is donewith techniques designed for datasets with random or completely random missingdata, as complete case analysis, mean imputation, regression imputation, maximumlikelihood or multiple imputation. However, the data conditions required to minimizethe bias derived from an incorrect analysis have not been fully determined. In thepresent work, several Monte Carlo simulations have been carried out to establishthe best strategy of analysis for random missing data applicable in datasets withnonrandom missing data. The factors involved in simulations are sample size,percentage of missing data, predictive power of the imputation model and existenceof interaction between predictors. The results show that the smallest bias is obtainedwith maximum likelihood and multiple imputation techniques, although with lowpercentages of missing data, absence of interaction and high predictive power ofthe imputation model (frequent data structures in research on child and adolescentpsychopathology) acceptable results are obtained with the simplest regression imputation.  相似文献   

4.
Analysis of covariance techniques have been developed primarily for normally distributed errors. We give solutions when the errors have non-normal distributions. We show that our solutions are efficient and robust. We provide a real-life example.  相似文献   

5.
Over the last two decades, due to strong decentralization and widespread budget constraints, the Italian co-payment for health care has become a way to finance public health. This phenomenon has provoked a continuous increase of private costs of public health and an evident regional heterogeneity. As a result, a pervasive spatial inequality of access to public health care is becoming increasingly clear. The aim of this paper is to measure this inequality, mainly determined by the differences among regional co-payment prices. Access, equity, and needs are all part of the phenomenon ‘inequality of access’, and they are difficult to define and measure in health care. For this reason, most of the previously proposed measurement methods have inherent limitations and have prompted us to use an innovative approach focused exclusively on the supply side. In particular, we focus only on the cost of health benefits (co-payment). From a methodological perspective, we use a recent new version of the Stochastic Multiobjective Acceptability Analysis (SMAA), which is a methodology mainly used to build composite indicators of multidimensional phenomena out of the market. In order to deal with the hierarchical structure of the Italian health care system, we use the Hierarchy Stochastic Multiobjective Acceptability Analysis (HSMAA), which takes into account the uncertainty with respect to the weights assigned to the considered criteria, as in the standard SMAA, but also the uncertainty with respect to the weights assigned to the considered sub-criteria. Applying for the first time HSMAA to measure inequality allows us to create a unique index for each region and then to make a classification among them. The results show that, since there are different prices for the same health benefits among different regions, there are strong spatial inequalities in the cost of the Essential Levels of health care in Italy.  相似文献   

6.
杨丽  黄斌 《价值工程》2011,30(10):88-88
本文以某研发中心设计为例,对该研发中心的建筑布局、交通组织、平面设计、造型设计和先进的建筑设备技术五大方面进行了详细阐述。  相似文献   

7.
本文针对某一客运枢纽站这一特殊工程设计,给出了建址的选取三原则,对建筑造型的整体进行了叙述,充分体现出钢结构的特色与优势。在此基础上个对结构设计进行了说明,屋顶采用网架结构体系,既实现了轻屋面的结构设计理念,又保证了室内的自然采光,显得宽敞明亮,给人舒服高雅的感觉。可为开展同类工程设计提供参考。  相似文献   

8.
卢振忠 《价值工程》2011,30(13):64-64
本文结合北方冬季情况,设计分析了一种新型的除雪机。  相似文献   

9.
冉群  王卫争 《价值工程》2011,30(36):61-62
对某高层建筑火灾后的现场调查内容和检测方法、结果进行介绍,通过分析检测结果,综合评定了结构的受损情况,并制定了结构修复加固设计方案。  相似文献   

10.
张连瑞  张立欣 《价值工程》2022,41(2):118-120
针对目前仓库货物取放工作效率低、劳动强度大且存在安全隐患等问题,本文借鉴传统的椅子及梯子的结构及功能,基于组合创新方法创新设计一种移动式仓库上货椅梯。该装置将椅子和梯子的功能合为一体,移动方便且稳定可靠,成功解决梯子靠在货架上易将货架压倒、椅子的高度不够、稳固性差、梯子及椅子搬运不便、移动性差等问题,提高了仓库取放货物的工作效率,应用推广前景广阔。  相似文献   

11.
程操  安昌浩 《价值工程》2013,(17):46-47
对低压双电压变压器的设计思路进行分析,并举例进行例证。  相似文献   

12.
顾锋 《价值工程》2015,(18):68-70
本文对上涌公园站~大塘站盾构区间的风险工程进行了设计分析,阐述了风险工程的主要设计原则,提出了对应具体风险的针对性措施。同时本文着重对下穿地铁3号线大塘站的风险工程进行了方案的比选分析及数值模拟,并提出了盾构施工的监测方案以监控施工影响、指导施工。  相似文献   

13.
文章围绕学校实行学分制以后,如何能兼顾体系性教学与开放式教学二者的优点,为最终形成“基础宽厚、特色明晰”的工业设计人才培养提供基础这一问题进行了探讨。  相似文献   

14.
文章围绕学校实行学分制以后,如何能兼顾体系性教学与开放式教学二者的优点,为最终形成"基础宽厚、特色明晰"的工业设计人才培养提供基础这一问题进行了探讨。  相似文献   

15.
郝丽娜  客贵宾 《价值工程》2011,30(32):103-103
结合某一跨度为72m的桁架桥设计,给出了截面和材料的选取,采用大型有限元软件ANSYS进行了该桁架桥的仿真分析,介绍了建模、约束和加载的过程,得到了杆件的内力,验算了杆件的承载力和桥的整体变形,为同类桥梁结构的设计与分析提供参考和借鉴。  相似文献   

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