The next step evaluated the proportionality assumption for each of the covariates by comparing a model with time-varying covariate effects (non-proportional) to a model that constrained the covariate effects to equality (proportional). The only variable that resulted in a significantly better model fit when allowed to vary across time was Time 1 age (χ2 = 33.108, df=6, p=.01). The parameter estimates and odds ratios for the univariate effects of age (allowed to vary across time) and the other five covariates (assumed to be proportional) are listed in Table 2 under the Univariate Effects heading. All covariate effects, except for BMI, were significant in the expected direction: LR to alcohol and age of alcohol onset were negatively related to the hazard function such that a low LR and an earlier age of alcohol onset were associated with AUD occurrence; family history of AUD and T1 typical quantity were positively related to the hazard function such that having an alcoholic parent and higher levels of baseline drinking were associated with AUDs across adulthood; and there was a negative relation between T1 age
