Fitting Structural Equation Model Trees and Latent Growth Curve Mixture Models in Longitudinal Designs: The Influence of Model Misspecification

When conducting longitudinal research, the investigation of between-individual differences in patterns of within-individual change can provide important insights. In this article, we use simulation methods to investigate the performance of a model-based exploratory data mining technique—structural equation model trees (SEM trees; Brandmaier, Oertzen, McArdle, & Lindenberger, 2013)—as a tool for detecting population heterogeneity. We use a latent-change score model as a data generation model and manipulate the precision of the information provided by a covariate about the true latent profile as well as other factors, including sample size, under the possible influences of model misspecifications. Simulation results show that, compared with latent growth curve mixture models, SEM trees might be very sensitive to model misspecification in estimating the number of classes. This can be attributed to the lower statistical power in identifying classes, resulting from smaller differences of parameters prescribed by the template model between classes.     

环氧树脂改性沥青混合料性能试验研究

为了解我国自主研制的环氧树脂改性沥青混合料的路用性能,采用马歇尔、劈裂、车辙、小梁弯曲和复合梁疲劳等试验,对其材料特性和路用性能进行了全面的试验研究,并与SMA10混合料的性能进行了对比研究.车辙和复合梁疲劳试验结果表明,环氧树脂改性沥青混合料具有良好的高温稳定及疲劳性能;与SMA10混合料相比,环氧树脂改性沥青混合料具有良好的抗水损害及低温抗开裂性能.研究表明,新型国产环氧树脂改性沥青混合料以其优异的性能和良好的经济优势为我国大跨径钢桥桥面铺装提供了一种新的铺装材料.     

非共沸环保混合制冷剂自然复叠冷柜的可行性研究

针对非共沸环保混合制冷剂(R744/R717)自然复叠制冷-40℃冷柜模拟研究结果,在进一步探讨了该系统的变工况特性的基础上,提出应对冷却介质温度发生变化的系统控制方案及应对压缩机过热的系统改进方案.     

明清时期“西学”与中国学术的交融

“西学东渐”始于17世纪，它掀起中国文化交流的又一个高潮。明末清初西学对中国学术思想的发展有一定程度的影响。清初以后由于统治者的愚昧和保守，西学传入的规模和内容均不及前期。从比较中看出，文化融合的先决条件在于对其价值体系的认同。     

Effect Analysis Using Nonlinear Structural Equation Mixture Modeling

In this article, we present an approach for comprehensive analysis of the effectiveness of interventions based on nonlinear structural equation mixture models (NSEMM). We provide definitions of average and conditional effects and show how they can be computed. We extend the traditional moderated regression approach to include latent continous and discrete (mixture) variables as well as their higher order interactions, quadratic or more general nonlinear relationships. This new approach can be considered a combination of the recently proposed EffectLiteR approach and the NSEMM approach. A key advantage of this synthesis is that it gives applied researchers the opportunity to gain greater insight into the effectiveness of the intervention. For example, it makes it possible to consider structural equation models for situations where the treatment is noneffective for extreme values of a latent covariate but is effective for medium values, as we illustrate using an example from the educational sciences.     

A Technique for the Construction of a Teacher-Training Curriculum

ABSTRACT

Historically, students who fail to graduate from secondary school are considered as a single category of school dropouts. However, emerging literature indicates that there may be multiple subgroups of high school dropouts, termed a dropout typology. The authors’ purpose was to assess the extent to which a typology of dropouts was present in a large national dataset and to estimate the influence of the known covariates of dropping out on each of the subgroups. A growth mixture model was estimated using the Education Longitudinal Study 2002 (National Center for Education Statistics, n.d.) dataset and noncumulative grade point average during the first 3 semesters of high school. The model identified 2 main subgroups associated with dropping out, which accounted for 24.6% of the sample but contained 91.8% of the dropouts.     

源远流长的民族历史文化情结——姚安高氏土司与丽江木氏土司友好交往初探

云南姚安高氏和丽江木氏两大家族很早就建立了深厚的氏族同盟,他们在政治上联手,经济上互通有无,文化上取长补短,家族间友好联姻,共同携手谱写了世代友好、精诚团结的优美乐章,在云南经营和开拓了美丽的家园,演绎了很多动人的民族政治和历史文化传奇轶事,成为耸立在丽(江)姚(安)两地耀古烁今的民族友谊丰碑。     

悲剧的命运 悲壮的人生浅析瓦吉姆形象

瓦吉姆与“恶魔”和“多余人”一样,具有强烈的叛逆性。他身上洋溢着尖锐的暴动的情绪和阴沉的复仇的激动。而且,在他身上,还存在着鲜明而尖锐的爱恨交织、善恶交叉的性格矛盾。他的复仇失败了,但他果敢的斗争精神留给我们的却是英雄般的悲壮。     

一种自适应的基于混合高斯模型的运动目标检测算法

为提高运动目标检测的可靠性,提出了一种自适应的基于混合高斯模型的运动目标检测算法．该算法利用混合高斯分布对每个背景像素建模,高斯分布的个数不是固定不变的,而是随着像素值的混乱程度自适应变化．差分图像的像素按大小被分为2部分,然后对这2部分分别进行自适应阈值化分割,得到前景图像．利用基于形态学重构的阴影消除方法来改善前景图像分割的性能．不同实际场景的实验结果表明该算法能够快速准确地建立背景模型,且具有更强的鲁棒性．     

Different pathways towards dropout: the role of engagement in early school leaving

In this study, we examine the development of student engagement in relation to dropout. We focus on different growth trajectories of engagement between groups of students and on whether these trajectories lead to differences in the survival of the student. The development of behavioural and emotional engagement of 4063 graduates and 541 (11.7%) dropouts is examined from Year 7 to Year 12 and this development is linked to the probability of dropping out in each grade by means of a discrete-time survival mixture model. For emotional engagement, results point to a model with two different subgroups: one group starting at a high level of engagement and following a (relatively) stable pattern and the other group starting at a lower level of engagement and following a decreasing trend. For behavioural engagement, the results indicate that a three-class model showed the best fit: a high and (relatively) stable group, a high and decreasing group and a low and stable group. In terms of dropout, the unstable and low groups demonstrate a significantly higher probability of dropping out, as evidenced in the steep, declining survival curves. Different background variables are included to gain more insight into engagement and dropout, and to predict membership in the low and decreasing class.