For the latent class models, the proportion of individuals expected in each class was given by the class proportion parameters (δ). Measurement parameters, ρ, represent the probability of an individual reporting a certain level of DrInC, PDD, and DDD conditional on class membership. For LTA, the transition probabilities, τ, represent the transitions between latent drinking classes. The τ parameters describe the probability of class membership at one time point, conditional on the probability of class membership from the previous time point (e.g., first-order model). See Chung et al. (2005) for an explication of the model. For LTA with covariates, the β parameters describe the distribution of latent drinking classes, conditional on alcohol dependence. The β parameters can be given as odds ratios that represent the probability of class membership at each time point relative to the odds of class membership of the specified reference class.
