For the tests of the rapidity of the transition from regular alcohol use to alcohol dependence as a function of the age onset of regular alcohol use, those who become regular alcohol users in the youngest age range were much more likely to become alcohol dependent either in the same age range or the subsequent age range than those who become regular alcohol users in the age ranges 16–17 years or 18–19 years (using Fisher’s exact test). Viewing this from a slightly different perspective, the fraction of those who transition from alcohol use to alcohol dependence in less than 2 years in the oldest age range is much smaller than that in the youngest age range. A Cochran-Armitage trend test of this phenomenon shows a p-value of less than 8 × 10−5 for the hypothesis of no trend.
