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J A Green 《Child development》1988,59(1):1-25
This article provides an introduction to loglinear analysis of cross-classification tables, including tables with nominal and ordinal variables. Loglinear models offer several advantages over the more commonly used chi-square test of independence, including the ability to analyze 3-, 4-, and higher-way interactions, the ability to determine whether the association between variables is linear or nonlinear, and the ability to interpret scale scores assigned to categories of an ordinal variable. After a review of the advantages of loglinear modeling, the chi-square test of independence is compared with the loglinear model of independence. This comparison serves to introduce the notation and terminology of loglinear modeling. The overall strategy of loglinear modeling is introduced next; then special loglinear models for ordinal data are reviewed. Each model discussed in the article is applied to data from the developmental literature. 相似文献
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条件回归独立性是指给定随机变量Z=z时,随机变量X的条件期望E(X/y,z)不依赖于y.本文讨论了条件回归独立性与条件随机独立性之间的关系,找到了两者等价的充分必要条件. 相似文献
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主题是独立的句法成分,在句法结构中具备独立的节点;主题的独立性可以找到理论依据;英语中位于句首的悬垂名词性成分不是嫁接的产物,故不受制于毗邻条件,实为独立主题;汉语也具备独立的,不受毗邻条件制约的主题;被与其紧邻的比较短语修饰是主题独有语法特征。 相似文献
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GIS-based logistic regression method for landslide susceptibility mapping in regional scale 总被引：12，自引：0，他引：12
ZHU Lei HUANG Jing-feng 《浙江大学学报(A卷英文版)》2006,7(12):2007-2017
INTRODUCTION Landslide is one of the most serious geological hazards in mountain areas. Globally, they cause hundreds of billions of dollars in damage, and hun- dreds of thousands of deaths and injuries each year (Aleotti and Chowdhury, 1999). Over the past fewdecades, scientists have shown an ever increasing interest in this natural hazard. One of the study fields is to produce landslide susceptibility map, i.e. a map portraying the spatial distribution of the future susceptibility of s… 相似文献
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针对设备故障预测模型难以精确建立的特点,为提高故障间隔时间预测的精确度,提出了变周期三角函数-灰色模型GM(1,1)的预测方法。该方法在三角函数-灰色模型GM(1,1)基础上,建立了变周期三角函数—灰色GM(1,1)的组合模型,实现了对设备故障间隔时间的预测;并将预测结果与三角函数-灰色模型GM(1,1)进行对比,结果表明,采用变周期三角函数-灰色模型GM(1,1)对故障间隔时间进行预测,其预测结果的相对误差由24.16%降到3.24%,提高了预测结果的精度。 相似文献
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万冬梅 《襄樊职业技术学院学报》2010,9(5):27-28
二维随机变量独立性的判别法一般文献中都有,但方法不很简便。本文给出了一个简单的判断方法并证明其存在的合理性,而且推广至n维随机变量独立性的判别方法。 相似文献
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Berta Weiss Hattwick 《Journal of Experimental Education》2013,81(2):180-190
The power of analysis of covariance (ANCOVA) and 2 types of randomized block designs were compared as a function of the correlation between the concomitant variable and the outcome measure, the number of groups, the number of participants, and nominal power. ANCOVA had a small but consistent advantage over a randomized block design with 1 participant in each Block × Treatment combination (RB1). At correlations of .3 or greater, ANCOVA was superior to a randomized block design with n participants per Block × Treatment combination (RBn), with increasing differences as the correlation increased. RBn was superior to the other 2 designs only when the correlation was .2 or less. At those levels, however, the randomized group analysis of variance ignoring the concomitant variable was equally powerful. The findings held regardless of sample size, number of groups, or nominal power. 相似文献
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Jens‐Peter Gaul 《Higher Education in Europe》2005,30(2):167-171
Assessments such as ranking exercises arguably level the playing field for stakeholders. Quality assurance may remain a challenge for consumers, but ‘public’ assessments do provide a nominal element of independence or autonomy. This article outlines, from a German perspective, the way in which research assessments are frequently subject to influence from a variety of sources. It offers some developmental perspectives on assessment as an organic work‐in‐progress for the scientific and research community. 相似文献
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李利 《湖南师范大学社会科学学报》2012,41(4):109-113
利用1990-2009年全国层面不同类型工业行业的结构数据,分别选用人民币名义有效汇率和实际有效汇率作为解释变量,综合采用一系列时间序列处理方法,系统考察了人民币汇率波动对不同密集型行业结构的影响.研究表明,人民币升值对劳动密集型行业发展产生一定的抑制作用,而对资本密集型和技术密集型行业发展则具有较为显著的促进作用;且实际有效汇率对三类行业结构的影响显著大于名义有效汇率的影响. 相似文献
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因应产业外移导致结构性的失业,失业者更需要投资职能训练增加其就业率。金融风暴的来临,失业率攀高,行政当局投资大量训练费用予职训主管机构提供训练课程,但是成效与否与投资成本之间确切关系必须有一准确计算公式,使失业者及行政当局能在有限投资成本下提高就业率,故本论文研究弹性职能训练费用与成效率之最佳预测模式。配合信息科技之到来,弹性职能训练费用与其成效率之计算公式,未来可输入在民间及行政当局与职训业者计算机应用程序中,作为控制成本找出最大的就业率。 相似文献
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文章运用福建省1986-2012年产业结构与环境污染的相关指标与数据,构建VAR模型,对产业结构调整与环境污染关系进行实证研究,结果表明:产业结构调整与环境污染之间有着相互的作用,产业结构调整是环境污染预测方差的重要变量,而第二产业内部的重工业结构又是环境污染预测方差的重要变量,即产业结构调整将导致环境污染的加剧,尤其是第二产业内部的重工业结构对于环境污染有相当大的影响。针对分析,文章的最后提出福建省产业结构调整的相关对策建议。 相似文献
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卷积公式有离散型随机变量和连续性随机变量两种形式.文章介绍了卷积公式的另外一种证法,并用其证明了一些分布的可加性,尤其强调了可加性中随机变量相互独立的条件必不可少。 相似文献
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汉英语篇中省略的对比研究 总被引：1，自引：0，他引：1
省略现象包括名词性省略、动词性省略和小句性省略,在汉英两种语言使用广泛并表现出一定的相似性。但是,由于汉英两种语言存在差异,省略现象仍然有本质上的差异。 相似文献
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The primary goal of this study was to examine the science process skill of prediction using qualitative research methodology. The think-aloud interview, modeled after Ericsson and Simon (1984), let to the identification of 63 program exploration and prediction behaviors. The performance of seven formal and seven concrete operational high-school biology students were videotaped during a three-phase learning sequence on water pollution. Subjects explored the effects of five independent variables on two dependent variables over time using a computer-simulation program. Predictions were made concerning the effect of the independent variables upon dependent variables through time. Subjects were identified according to initial knowledge of the subject matter and success at solving three selected prediction problems. Successful predictors generally had high initial knowledge of the subject matter and were formal operational. Unsuccessful predictors generally had low initial knowledge and were concrete operational. High initial knowledge seemed to be more important to predictive success than stage of Piagetian cognitive development. Successful prediction behaviors involved systematic manipulation of the independent variables, note taking, identification and use of appropriate independent-dependent variable relationships, high interest and motivation, and in general, higher-level thinking skills. Behaviors characteristic of unsuccessful predictors were nonsystematic manipulation of independent variables, lack of motivation and persistence, misconceptions, and the identification and use of inappropriate independent-dependent variable relationships. 相似文献
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项海飞 《温州职业技术学院学报》2010,10(4):52-53
从指数分布的定义出发,根据连续型随机变量相互独立的充分必要条件,探讨一系列建立在服从指数分布的随机变量基础上的随机变量函数的独立性。结果表明,当母体服从指数分布时,子样次序统计量构成的随机变量函数相互独立,且这些随机变量所构成的线性函数与任一分式线性函数之间相对独立。 相似文献
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The purpose of this study was to examine the performance of differential item functioning (DIF) assessment in the presence of a multilevel structure that often underlies data from large-scale testing programs. Analyses were conducted using logistic regression (LR), a popular, flexible, and effective tool for DIF detection. Data were simulated using a hierarchical framework, such as might be seen when examinees are clustered in schools, for example. Both standard and hierarchical LR (accounting for multilevel data) approaches to DIF detection were employed. Results highlight the differences in DIF detection rates when the analytic strategy matches the data structure. Specifically, when the grouping variable was within clusters, LR and HLR performed similarly in terms of Type I error control and power. However, when the grouping variable was between clusters, LR failed to maintain the nominal Type I error rate of .05. HLR was able to maintain this rate. However, power for HLR tended to be low under many conditions in the between cluster variable case. 相似文献
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葛婷 《临沂师范学院学报》2009,31(2):120-123
协同副词的语义指向多个名词性成分,协同副词对名词性成分的要求在句法上必须是复数的．形式有有标记的和无标记的两种,语义关系有主从式和并列式两种;同时协同副词对名词性成分的语义有规约作用,名词性成分必须是有界的,且内部关系存在一个连续统：从典型的语义场到某种语义的相关性再到语用场的渐变过程。 相似文献