Zhiyong Zhang

Mediation models have been extensively studied and used in psychological research. Among the methods testing mediation effects, the bootstrap resampling method has been shown more effective than the large sample method in small sample research. In the current study, a modified bootstrap method is proposed which is based on resampling residual errors of the mediation models in the framework of path analysis. The proposed method is then compared with the large sample method and bootstrapping raw data method in different conditions. The results show that the bootstrapping error method  has better coverage probability and is more efficient than the bootstrapping raw data method when the residual errors are homogeneous. In the heteroscedastic case, the bootstrapping raw data method performs best among three methods regardless of sample size. A C++ program is provided to implement all three methods with the modified Brown-Forsythe statistic to test the homogeneity of residual errors.

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Steven Boker

Local linear approximation (LLA) has been used to provide explicit estimates of derivatives from three dimension time-delay embeddings of repeated observations data in order to fit differential equations models. This talk presents a method for constructing weight matrices for approximation of derivatives using arbitrary time-delay embedding dimensions. The method is shown to be equivalent to fixed loading matrices used in latent differential equations (LDE) modeling and growth curve modeling. An example data set from a study of ovarian hormones and disordered eating is used to apply 3, 6, 9, and 14 dimensional time--delay embedding and to calculate generalized local linear approximation (GLLA) of derivatives. Choices of embedding dimension lend increased flexibility to deal with issues of signal to noise ratio and patterns of missingness that may characterize a particular data set. Higher embedding dimensions also appear to help reduce the attenuation of interindividual differences in estimated period that occurs in three dimensional embedding used in LLA. Finally, the talk will present some speculation in how convolution kernels used in image processing might be used to identify transition points (edges) rather than smooth growth curves.

Click the link to view the schedules of DADA talks. http://www.cdhrm.org/article.php?articleid=83

Ryne Estabrook

Longitudinal data spanning 22 years, obtained from deceased participants of the German Socio-Economic Panel Study (SOEP; N = 1,637; 70 to 100 year olds), were used to examine if and how life satisfaction exhibits terminal decline at the end of life. Relative to distance from birth (i.e., chronological age), distance-to-death provided for a better fit to the data, suggesting that late-life changes in life satisfaction are characterized by relatively steep mortality-related declines. Multiphase growth models were used to identify a transition point roughly 4 years prior to death. Further analyses found improved fit by random effects models allowing for individually-varying change points, raising questions about the ergodicity of terminal decline.

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Lijuan Wang

Various policy papers assert that teamwork is one of the most important skills for the 21st Century workforce. However, outside of organizational psychology and adult populations, there are few reliable assessments of this construct, with suitable validity evidence. To redress this issue, teamwork assessments for high school students were developed using multiple methods: self-report ratings, situational judgment testing, and teacher reports. Exploratory factor, confirmatory factor, and latent class analyses were used to determine the structure of the scales. Measures showed reasonable reliability and promising validity evidence, relating to each other and to academic achievement, yet relatively independent from personality. The advantages and disadvantages of each methodology, and the potential applications for identification and intervention, selection, and evaluation of training programs are discussed.

Click the link to view the schedules of DADA talks. http://www.cdhrm.org/article.php?articleid=83