As a preliminary step before pooling the data, the frequency distributions of the 11 DSM-IV criteria and the prevalence of DSM-IV AUDs were examined separately for each survey year. Factor analytic (FA) models were used to test for the presence of a unidimensional trait of alcohol problem severity underlying the 11 DSM-IV AUD symptom criteria for each year of data. Exploratory factor analysis (EFA) was conducted by gender and age group for each survey year. The EFA results were then used to specify the factor structure in a multiple causes and multiple indicators (MIMIC) model (Joreskog and Sorbom, 1979) generalized to dichotomous outcomes (Muthén, 1979; Muthén, Tam, Muthén, et al., 1993). The MIMIC model used in this study is a special case of structural equation modeling, in which one or more latent variables intervene between a set of observed background variables (covariates) predicting a set of observed response variables (i.e., DSM-IV AUD symptom criteria). The MIMIC model includes three sets of relationships: those between the symptom criteria and the latent factors (the measurement model), those between the latent factors and
