Consistency between Time 1 and Time 2 in categorization as an early (vs. average to late) initiator of alcohol use is reported in Table 1. Although the tetrachoric correlation was in the moderate range (r=0.65), it is evident from the table that the association is driven by the high consistency among average to late onset users. Over 90% of individuals reporting at Time 1 that they began drinking at 15 years of age or older also reported initiating alcohol use at age 15 or later at Time 2. By contrast, fewer than half of the participants who reported onset of alcohol use before age 15 at the first assessment reported an onset age younger than 15 years at Time 2.
