Exploratory factor analyses was used for testing the unidimensionality of alcohol use disorders both in the merged ED sample as well as separately by site (Table 3). In the merged sample, all 11 criterions loaded significantly on a single dimension. A two factor solution produced one factor with all dependence items and one abuse item. The second factor had only two of the four abuse items. Both factors had a strong correlation (0.854) and the first eigenvalue was much larger than the second, all of which suggest that a single factor solution is a reasonable description of the data and that the 11 criterions formed a single, unidimensional trait in the merged ED patients. Inspection of the four samples did not show divergent conclusions. Among the U.S. and Mexican samples, a large correlation between the two factors and a small second eigenvalue suggest that unidimensionality is a reasonable and more parsimonious explanation for these data. The two factors solution for Santa Clara produced a first factor composed of all dependence items and one abuse item (hazardous use) while the second
