合理进行多重线性回归分析——结合倾向性评分分析

本文目的是介绍如何结合倾向性评分分析,合理地进行多重线性回归分析的方法。第一,介绍了与倾向性评分分析有关的3个基本概念。第二,介绍了倾向性评分分析的核心内容,即3种匹配方法。第三,通过一个流行病学的调查实例,介绍了如何用SAS软件进行分析的全过程,内容如下：(1)针对原始数据集,检验协变量在处理组与对照组之间的差异是否具有统计学意义;(2)针对原始数据集,直接进行多重线性回归分析;(3)采用倾向性评分分析产生匹配后的数据集;(4)针对匹配后的数据集,检验协变量在处理组与对照组之间的差异是否具有统计学意义;(5)针对匹配后的数据集,合理进行多重线性回归分析。     

合理进行多重Logistic回归分析——结合ROC曲线分析

本文目的是介绍如何结合ROC曲线分析,合理地进行多重Logistic回归分析的方法。第一,介绍了与ROC曲线分析有关的两组基本概念,即常用诊断指标的统计描述和诊断资料的ROC曲线分析方法。第二,介绍了ROC曲线分析中的核心内容,即ROC曲线下面积的计算和多条ROC曲线下面积的比较。第三,通过一个诊断试验的实例,介绍了如何用SAS软件进行分析的全过程,内容如下：(1)仅采用多重Logistic回归分析;(2)基于多重Logistic回归分析,再结合ROC曲线分析。得到的结论是,对于诊断试验资料,将多重Logistic回归分析与ROC曲线分析结合起来,可以获得更丰富、更合理的统计分析结果。     

合理进行多重Logistic回归分析——结合多水平模型分析

本文目的是介绍如何结合多水平模型分析,合理地进行多重Logistic回归分析的方法。第一,介绍了与多水平模型分析有关的4个基本概念。第二,介绍了构建多水平模型的3个步骤。第三,通过一个多中心药物临床试验的实例,介绍了如何用SAS软件进行分析的全过程,其内容如下：①检验各中心优势比之间是否具有齐性;②对试验中心产生哑变量后构建多重Logistic回归模型;③将试验中心视为分层变量构建多重Logistic回归模型;④构建随机截距多水平多重Logistic回归模型;⑤构建随机截距和随机斜率多水平多重Logistic回归模型。得到的结论是,当具有二值结果变量的各层级资料间存在差异时,最合适的做法是构建多水平多重Logistic回归模型。     

基于因果图模型应用调整集估计数据的因果效应

本文目的是介绍因果图过程的5个局限性和基于因果图模型应用调整集估计数据的因果效应。5个局限性包括：(1)因果图过程不能处理有向循环的因果图模型;(2)因果图过程不能评估动态处理方案;(3)因果效应识别是一个总体概念;(4)因果效应识别是一个非参数概念;(5)因果图过程不能识别某些因果图模型中的因果效应。实例是针对一个模拟的数据集,分别采用常规的多重Logistic回归模型分析与因果图模型分析,比较二者的分析结果,得出如下结论：(1)因果图理论在混淆情况下识别因果效应是有用的;(2)通过实施因果效应的分层估计,可以基于因果图过程的识别结果,实现因果效应的良好统计估计。     

基于正交化方法的回归分析

本文目的是介绍基于正交化方法的回归分析的概念、作用以及用软件实现计算的方法。先介绍有关的基本概念,再介绍基本原理,最后通过两个实例并基于SAS软件演示如何实施此分析方法。结果表明:(1)此法不能解决资料中存在多重共线性问题带来的坏影响;(2)此法能够很好地解决多项式回归分析问题。     

稳健回归分析

本文目的是介绍稳健回归分析的概念、作用以及用软件实现计算的方法。先介绍有关的基本概念,再介绍基本原理,最后通过两个实例并基于SAS软件演示如何实施此分析方法。结果表明:(1)此法不能解决资料中存在多重共线性问题带来的坏影响;(2)此法能够很好地解决资料中存在异常点的回归分析问题。     

加性与广义加性模型回归分析

本文目的是介绍加性与广义加性模型回归分析的概念、作用以及用软件实现计算的方法。先介绍有关的基本概念,再介绍基本原理,最后通过一个实例并基于SAS软件演示如何实施加性模型回归分析。结果表明:相对于引入派生变量进行常规多重线性回归分析而言,加性与广义加性模型回归分析能够更好地提升模型对资料的拟合效果。     

因果中介效应分析的关键技术和多向分解方法

本文目的是介绍因果中介效应分析的5项关键技术和效应成分多向分解方法。5项关键技术的内容如下：(1)因果中介效应的识别;(2)因果中介效应分析的回归方法;(3)最大似然估计;(4)总效应与各种成分效应的估计;(5)自助法估计。多向分解方法包括3个双向分解、2个三向分解和1个四向分解。本文通过一个实例,借助SAS构建包含协变量和交互作用项的因果中介效应模型,对因果中介效应分析中的总效应进行双向分解、三向分解和四向分解,并对输出结果进行解释。     

1∶r配对设计二值资料一水平多重Logistic回归分析

本文的目的是介绍"1∶1""1∶2"和"1∶r"配对设计二值资料一水平多重Logistic回归分析方法。统计分析的前提条件是资料值得分析,而确保配对设计二值资料值得分析的重要基础是"配对设计"科学合理。为此,本文从六个方面阐述"配对设计的要领",不仅介绍了构建"1∶1""1∶2"和"1∶r"配对设计二值资料一水平多重Logistic回归模型的方法,还通过三个实例,介绍了采用SAS软件实现统计分析及结果解释的详细步骤。     

协变量在因果中介效应分析中的作用

本文目的是介绍因果中介效应分析的理论基础以及结合一个实例采用SAS实现因果中介效应分析的具体方法。因果中介效应分析的理论基础包括基本概念以及定义因果中介效应的反事实框架。实例是关于父母提供的鼓励性环境是否会影响儿童的认知发展,分别采用传统的多重线性回归分析、不考虑协变量和考虑协变量的因果中介效应分析,通过比较3种分析方法所得到的结果,得出如下结论：①当资料中存在中介变量时,不适合采用传统的多重线性回归分析取代因果中介效应分析;②当资料中存在协变量时,不适合在忽视协变量的条件下进行因果中介效应分析。     

Assessment of handedness using latent class factor analysis

Recently several studies in which handedness was evaluated as a latent construct have been performed. In those studies, handedness was modelled using a qualitative latent variable (latent class models), a continuous latent variable (factor models), or both a qualitative latent variable and a continuous latent trait (mixed Rasch models). The aim of this study was to explore the usefulness and effectiveness of an approach in which handedness is treated as a qualitatively scaled latent variable with ordered categories (latent class factor models). This aim was pursued through an exploratory analysis of a dataset containing information on the hand used by 2236 young Italian sportspeople to perform 10 tasks. For comparison purposes, a latent class analysis was carried out. A cross-validation procedure was implemented. The results of all the analyses revealed that the best fit to the observed handedness patterns was obtained using a latent class factor model. Through this model, individuals were assigned to one of four ordered levels of handedness, and a quantitative index of left-handedness for each individual was computed by taking into account the different effect of the 10 tasks. These results provide support for the use of the latent class factor approach for handedness assessment.     

Survival analysis (or time to an event analysis), and the Cox regression model--methods for longitudinal psychiatric research

A multivariate statistical instrument is presented, which combines the life table with regression analysis: the Cox proportional hazards regression model. It is suitable for analyzing longitudinal clinical data, and to find predictors of different outcomes in psychiatric research such as death, relapse or cure. All patient information can be used, since the time to the outcome event is included in the model. Treatments can be compared, and prognostic indices created.     

An analysis and review of the literature and a three-tier video modeling intervention model

Many video modeling (VM) studies for teaching learners with autism have been published. Most studies have investigated the effectiveness of intervention; however, not all learners with autism respond to intervention in the same manner, and not all families and educators can afford such treatments. It is equally critical to address the delivery type of VM and the resources and support involved. This paper had 2 purposes: first, to review and analyze the literature regarding the characteristics of VM intervention and the video components for assisting practice and research; second, to develop a 3-tier VM intervention model (self-administered generic VM, group-based instruction, and individually administered individualized VM), based on the delivery types of intervention and the allocation of resources and support to address the factors that influence learners. Seven intervention characteristics and 7 video components were identified, and implications for future research regarding the 3-tier model were discussed.     

Methodological analysis of an experimental spinal cord compression model in the rat

A technique for producing graded spinal cord compression injuries in rats is described. A metal plate 2.2 x 5.0 mm in size is applied to the exposed spinal dura and loaded with weights. Neurological function is tested postoperatively on an inclined plane. Reading of the maximal angle of rat performance on this plane was found reproducible on comparison between different observers. Laminectomy per se had a minimal effect on the performance. Compression of 35 g for 5 min caused a pronounced but incomplete injury, with almost total recovery within 14 days and with no difference between animals on artificial respiration and those breathing spontaneously. Animals whose spine was fixed during the compression had a better outcome than those without such fixation.     

脑动静脉畸形出血危险因素的Cox回归分析

目的：探讨与脑动静脉畸形（ＡＶＭ）出血相关的临床及血管影像学特征，以期对脑ＡＶＭ的出血倾向作出评价和预测。方法：应用Ｃｏｘ回归模型，对５９例脑ＡＶＭ进行出血危险因素的单因素及多因素分析。结果：５９例脑ＡＶＭ中，观察期内出血４８例（占８１％），年平均出血率为２％；病灶大小、供应动脉支数以及引流静脉支数是决定脑ＡＶＭ出血倾向最重要的危险因素；小型ＡＶＭ、多支动脉供应的ＡＶＭ以及仅有单支静脉引流的ＡＶＭ最易破裂出血。结论：建议脑血管造影时着重对此三项指标进行描述；对于出血风险较大的脑ＡＶＭ应及早治疗。     

Asymmetry analysis of deformable hippocampal model using the principal component in schizophrenia

The hippocampus is thought to play an important role in learning and memory processing, and impairments in memory, attention, and decision making are found commonly in schizophrenia. Although many studies have reported decreases in hippocampal volume in the left hemisphere in schizophrenia, regionally specific hippocampal volume loss has not been revealed consistently using volume analysis. Recently, many studies have analyzed shape asymmetry using 3-D models; however, inconsistent results have been reported, mainly due to methodologic differences. We therefore used an active, flexible, deformable shape model for surface parameterization, and compared shape asymmetry based on principal component analysis (PCA) in the hippocampi of schizophrenic patients with those of the normal controls. Although the overall pattern of the statistical results did not change according to the number of principal components, the reconstructed results based on six major components were much more distinguishable. Although the left hemispheric hippocampal volume was larger than the right hemispheric was in this study, the difference was not significant. In shape asymmetry analysis, the right hemisphere hippocampus was bilaterally larger than the left hemisphere hippocampus was in the head of the superior CA1 and smaller in the tail and head of the inferior CA1. The asymmetry in the schizophrenia group was statistically smaller than that in the control group through reduction of the left hemisphere hippocampus volume.