Using Stata a Plug-in to Estimate Group-Based Trajectory Models

1. Using Stata a Plug-in to Estimate Group-Based Trajectory Models Daniel S. Nagin Carnegie Mellon University

2. Installing the Plug-in Traj can be installed by issuing the following commands within Stata. An additional command, trajplot, supports plotting the results. . net from http://www.andrew.cmu.edu/user/bjones/traj . net install traj, replace

3. 4% 28% 52% 16%

4. Calculation & Use of Posterior Probabilities of Group Membership Maximum Probability Group Assignment Rule

5. Group Profiles

9. Logit Model for Binary Data where y=1 if yes & y=0 if no

10. Trajectories of Delinquent Group Membership(Development & Psychopathology, 2003)

12. Statistically Linking Group Membership to Individual Characteristics (Chapter 6) • Use of Multinomial Logit Model to Create a Multivariate Probabilistic Linkage

13. Risk Factors for Physical Aggression Trajectory Group Membership • Broken Home at Age 5 • Low IQ • Low Maternal Education • Mother Began Childbearing as a Teenager

17. Does School Grade Retention and Family Break-up Alter Trajectories of Violent Delinquency Themselves?(Nagin, 2005; Development and Psychopathology 2003)

18. The Overall Model Z1 Z2 Z3 Z4 Z5 ………. …. Zm Probability of Trajectory Group Membership Trajectory 1 Trajectory 2 Trajectory 3 Trajectory 4 X1t X2t X3t……………Xlt

19. Model of Impact of Grade Retention and Parental Separation on Trajectory Group j Model without retention or separation impact: Trajectory with retention and separation impacts:

22. Dual Trajectory Analysis: Trajectory of Modeling of Comorbidity and Heterotypic Continuity (Nagin and Tremblay, 2001; Nagin (2005)

23. Modeling the Linkage Between Trajectories of Physical Aggression in Childhood and Trajectories of Violent Delinquency in Adolescence

24. Transition Probabilities Linking Trajectories in Adolescent to Childhood Trajectories Trajectory in Adolescence Trajectory in Childhood

26. The Dual-Trajectory Model Generalized to Include Predictors of Conditional Probabilities • Are drug use and family break-up at age 12 predict the conditional probabilities linking childhood physical aggression trajectories with adolescent violent delinquency trajectories? • Answer: yes for drug use but no family break-up • Conditional probabilities specified to follow a “constrained” multinomial logit function (see section 8.7 of Nagin)

27. Probability of Transition to Chronic Trajectory Depending on Drug Use at Age 12 and Childhood Physical Aggression Trajectory

29. Multi-Trajectory Modeling

30. Linking Trajectories to Later Out Comes—Trajectories of Physical Aggression from 6 to 15 and Sexual Partners at 16

32. Adding Subject Attrition to the Model Probability of Death by Trajectory Group