For the twin sample, a single factor model adequately accounted for the covariation among the consumption measures, based on Eigenvalues and scree plots. All five items had substantial factor loadings, with loadings of similar magnitude in the young adult twin cohort (0.69–0.92 for women; 0.68–0.93 for men) and the older spouse cohort (factor loadings: 0.59–0.83 for women; 0.57–0.93 for men). In all cases, typical consumption during the period of heaviest use had the highest factor loading and frequency of intoxication during the period of heaviest use the lowest. Eight-year test-retest correlations in the spouse cohort were 0.76 in women and 0.78 in men.
