"Marketing has an image problem. Media-savvy millennials, and their younger Gen Z counterparts, no longer trust advertising, and they demand increased social responsibility from their brands--while still insisting on cutting-edge products with on-trend design. As always, brands need to be...

Group-based trajectory models are used to investigate population differences in the developmental courses of behaviors or outcomes. This note introduces a new Stata command, traj, for fitting to longitudinal data finite (discrete) mixture models designed to identify clusters of individuals...

This article reports on an extension of group-based trajectory modeling to address nonrandom participant attrition or truncation due to death that varies across trajectory groups. The effects of the model extension are explored in both simulated and real data. The analyses of simulated data...

This article is a follow-up to Jones, Nagin, and Roeder (2001), which described an SAS procedure for estimating group-based trajectory models. Group-based trajectory is a specialized application of finite mixture modeling and is designed to identify clusters of individuals following similar...

This article introduces a new SAS procedure written by the authors that analyzes longitudinal data (developmental trajectories) by fitting a mixture model. The TRAJ procedure fits semiparametric (discrete) mixtures of censored normal, Poisson, zero-inflated Poisson, and Bernoulli distributions...