Latent transition analysis and how it can address prevention research questions

The objective of this chapter is to introduce latent transition analysis (LTA) to the substance use prevention research community. LTA is a new methodological technique for testing stage-sequential models, such as models of substance use onset. LTA estimates several different sets of parameters. One of these sets is the transition probability matrix, which contains information about the probability of movement between stages in the model. LTA can be used to evaluate the effectiveness of prevention intervention programs by comparing the transition probability matrices of the program and control groups. If the prevention program is successful, the transition probability matrices will indicate that the probability of moving to a more advanced stage of drug use is lower for the program participants than for the control group. An advantage of taking a stage-sequential approach is that examining the transition probability matrix reveals how effective a program is for individuals entering the program with different levels and types of substance use experience. In this chapter, LTA is used to evaluate a variety of models of the early onset process separately for Anglo, Latino, and Asian-American adolescents, measured in seventh grade and again in eighth grade. Although somewhat different models are found to fit the three ethnic groups best, the differences likely are due to differences in the overall amount of substance use experience. Based on these results, it is suggested that, to be most effective, prevention programs should take place earlier for Anglos and Latinos, and later, followed by boosters, for Asian Americans.