A comparison of two latent variable causal models for adolescent drug use.

The competing simplex (involvement) and common factor models for youthful drug use are statistically compared using causal modeling with latent variables methods in a sample of 1,634 young adolescents. Latent variables of alcohol, marijuana, and other illicit drug use were confirmed and causally interconnected in a set of states. The confirmatory factor and the simplex stage models were found to be acceptable representations of the observed data according to both statistical and psychometric criteria. The results are discussed in terms of their implications for theories of emerging lifestyles including drug use, methodology, and policy about psychoactive substances.