The 9th Day of the LCSR Summer School: Between-Group Comparison of Trajectories

On Thursday, Prof. Kenneth Bollen addressed more complicated latent curve models. The lecturer talked about the between-group comparison of trajectories (for example, comparison between control and experimental groups). During the preceding three days the participants learned models based on the assumption that there are only individual deviations from the trajectory estimated on the whole sample. In contrast to these models, group analysis presupposes the presence of systematic differences in group dynamics. Furthermore, Prof. Kenneth Bollen presented two main approaches to revealing these differences. One of these approaches is based on including interaction terms between group dummy and explanatory variables. This inclusion allows for fixed slopes. According to the second approach, different models are estimated separately for each group. The latter approach takes into account the different variances of the group random effects and the possible individual trajectories divergences. Moreover, the participants learned how to apply unknown group membership modeling.