Given strong evidence of the unidimensionality of AUD from prior studies (Harford et al., 2009; Kahler et al., 2006, 2009; Proudfoot et al., 2006; Saha et al., 2006, 2007), the fit of a single-factor model was tested by means of exploratory and confirmatory factor analyses using Mplus software (Muthén and Muthén, 2004). Severity threshold parameters for the latent trait of AUD were estimated from a two-parameter logistic model using the BILOG-MG statistical program (Scientific Software International, 2003, see more detail in Saha et al., 2006). Mean values for number of criteria endorsed and validating measures were estimated using SUDAAN (Research Triangle Institute, 2004), a software program that uses Taylor-series linearization to adjust variance estimates for complex design characteristics. SUDAAN multiple linear and logistic regression analyses were used to obtain the net associations of each criterion with the validating measures and to estimate the proportion of variance explained by the simple count of criteria endorsed and an alternate count in which each endorsed criterion was weighted by its severity threshold parameter.
