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951.
如何描述发展趋势的差异:潜变量混合增长模型 总被引:1,自引:0,他引:1
在追踪研究中,研究者不仅关心某一特质随时间的发展趋势,而且关注个体之间发展趋势的差异及其存在差异的原因。在总体发展同质的情形下,多层线性模型和潜变量增长曲线模型为解决这一问题提供了切实有效的方法。但是如果所研究的总体本身不同质,就需要一种能够描述总体中不同质子总体的不同发展特点的方法。该文简要介绍了一种能够描述不同群体不同发展趋势特征的统计模型——潜变量混合增长模型,并通过一个实际例子介绍了这一方法的应用过程,同时说明了潜变量混合增长模型与多层线性模型和潜变量增长曲线模型之间的关系 相似文献
952.
孤独症神经结构研究中近来一个重要的发现是,孤独症生命早期存在脑过度生长的现象。进一步的探查表明,孤独症个体脑的过度生长主要由脑白质的过度生长造成,并且脑的过度生长又主要体现于那些较晚成熟的高级脑区。这一研究成果有助于孤独症儿童的早期发现和诊断,也提示孤独症并不是由单一的局部神经缺陷造成,其存在着广泛分布式的神经发展障碍 相似文献
953.
潜变量交互效应建模方法演变与简化 总被引:2,自引:0,他引:2
综述了近年来加入乘积指标的潜变量交互效应建模方法, 从产生乘积指标的策略、参数约束方法、均值结构与指标中心化的关系三个方面, 讨论了建模方法的简化进程。最后总结出同类方法中比较简洁又不失精确的潜变量交互效应建模方法—— 无需均值结构的无约束方法, 并给出了建模 步骤。 相似文献
954.
Age differences in the prevalence of physical aggression among 5-11-year-old Canadian boys and girls
It has been proven extremely difficult in the past to estimate the prevalence of physical aggression in children for two main reasons: (a) a heterogeneous sampling of behaviors (i.e., mix between physically aggressive and non-physically aggressive antisocial behaviors), and (b) a lack of a "gold standard" to identify children who exhibit physically aggressive behaviors on a frequent basis. The goal of this study was to test for age differences in the prevalence of physical aggression in the Canadian population of school-aged boys and girls, using cross-sectional data from the National Longitudinal Survey of Children and Youth (NLSCY). The first wave of the NLSCY included a representative sample of 12,292 Canadian children aged 5-11 years. We used latent class analysis to identify children whose propensity to exhibit physically aggressive behaviors was much higher than that of other children of the same age and sex in the population. The prevalence of physical aggression was estimated at 3.7% in 5-11-year-old boys and ranged from .5% to 2.3% in 11 and 5-year-old girls, respectively. Hence, the results show a decreasing trend in the prevalence of physical aggression with age for girls, but not for boys. These findings suggest the importance of considering the developmental pathways of physical aggression for boys and girls separately. 相似文献
955.
The impurity of measures is considered as cause of erroneous interpretations of observed relationships. This paper concentrates on impurity with respect to the relationship between working memory and fluid intelligence. The means for the identification of impurity was the fixed-links model, which enabled the decomposition of variance into experimental and non-experimental parts. A substantial non-experimental part could be expected to signify impurity. In a sample of 345 participants error scores and reaction times, which were obtained by the Exchange Test, represented working memory, and Advanced Progressive Matrices served as measure of fluid intelligence. The four independent latent variables of the model associated with error scores and reaction times led to a multiple correlation .67 with the latent variable of fluid intelligence. However, there was impurity since the decomposition by means of the fixed-links model showed that only 45% of the common variance was due to working memory. 相似文献
956.
A cross-domain latent growth curve model was used to examine the trajectories of change in student perceptions of four critical dimensions of school climate (i.e., teacher support, peer support, student autonomy in the classroom, and clarity and consistency in school rules and regulations) among 1,451 early adolescents from the beginning of sixth through the end of eighth grade; and the effects of such trajectories on the rate of change in psychological and behavioral adjustment. Findings indicated that all of the dimensions of perceived school climate declined over the 3 years of middle school. Furthermore, declines in each of the dimensions of perceived school climate were associated with declines over time in psychological and behavioral adjustment. Moreover, the direction of effects between each dimension of perceived school climate and psychological or behavioral adjustment were often unidirectional rather than bi-directional, underscoring the role of perceived school climate in the psychological and behavioral health of early adolescents. Gender and socioeconomic class differences in these patterns are noted. 相似文献
957.
958.
In the context of structural equation modeling, a general interaction model with multiple latent interaction effects is introduced.
A stochastic analysis represents the nonnormal distribution of the joint indicator vector as a finite mixture of normal distributions.
The Latent Moderated Structural Equations (LMS) approach is a new method developed for the analysis of the general interaction
model that utilizes the mixture distribution and provides a ML estimation of model parameters by adapting the EM algorithm.
The finite sample properties and the robustness of LMS are discussed. Finally, the applicability of the new method is illustrated
by an empirical example.
This research has been supported by a grant from the Deutsche Forschungsgemeinschaft, Germany, No. Mo 474/1 and Mo 474/2.
The data for the empirical example have been provided by Andreas Thiele of the University of Frankfurt, Germany. The authors
are indebted to an associate editor and to three anonymous reviewers ofPsychometrika whose comments and suggestions have been very helpful. 相似文献
959.
Distracted driving leads to performance changes in both longitudinal and lateral control. However, driving performance, being a multidimensional phenomenon, is very difficult to be interpreted from individual performance measures. The present study aimed to exhibit the distraction impacts on overall driving performance estimated by a single measure rather than assessing distraction effects on individual performance metrics such as speed, acceleration, lateral variation, etc. The study also focused on modelling and quantifying the impacts of overall deteriorated driving performance on crash risk. To achieve the objectives, a comparative analysis of investigating phone and music player usage was conducted using Structural Equation Modelling (SEM). In total, 90 drivers’ demographic details and driving performance data in distracted and non-distracted driving environments were collected. Firstly, the latent variable “performance degradation” was derived from longitudinal and lateral performance measures. Then the structural model revealed a positive relationship between the distractions and the overall performance degradation. Finally, the crash risk was modelled against the presence of distraction and performance degradation. With a factor loading of 0.29, the impact of deteriorated driving performance (i.e., indirect impact) was found to be the highest among all the contributory factors of the crash risk. Further, the results showed that among the distractions (i.e., direct impact), texting had the highest impact (factor loading = 0.28) on crash risk followed by visual-manual tasks related to music player (factor loading = 0.21). Thus, the present study quantified the effects of deteriorated driving performance caused by distracted driving on the crash risk. Further, the study also presented quantified effects of each distracting activity on the crash risk which accounted for the factors that could not be considered through the performance degradation measure. The approach used in the present study can be adopted in designing the countermeasures using advanced driver warning systems. 相似文献
960.