Pages

Friday, August 14, 2015

Latest New Zealand Study Reeks of Junk Science

A recent study has come out that supposedly shows a long-term increase in "serious traffic crashes" among 18-19 year olds in New Zealand following the lowering of their drinking age from 20 to 18 in 1999.  Previous studies found only a short-term effect, if even any effect at all.  But upon closer inspection, there is far less here than meets the eye.

First and foremost, the maxim that correlation does not prove causation holds true for any observational study of this nature, especially with such relatively modest "effect sizes".  Secondly, the study used 20-24 year olds as the comparison group, and we at Twenty-One Debunked have repeatedly noted how doing so is problematic in light of Dee and Evans (2001), Asch and Levy (1987 and 1990), and Males (1986), who found that raising the drinking age to 21 merely redistributed (i.e. delayed) some traffic deaths from 18-20 year olds to 21-24 year olds after controlling for a host of other variables.  There is no reason to believe that the reverse couldn't happen when drinking ages are lowered.  Thirdly, the study in question did not actually show an absolute increase in traffic crashes among 18-19 year olds, only a relative "increase" relative to 20-24 year olds as both decreased dramatically but decreased faster for the latter group.  Finally, the study found no evidence of a "trickle-down" or spillover effect on 14-17 year olds despite the fact that NZ doesn't even have a hard drinking age, but rather just a purchase age of 18 with rather shoddy enforcement.  Though since 2013, the loophole that allowed furnishing to minors was partially closed among other changes, but the study does not include any data beyond 2010.

Furthermore, another recent study casts further doubt on the claim that lowering the drinking age led to any sort of "parade of horrors" that the pro-21 crowd likes to claim occurred as a cautionary tale.  Put simply, lowering the drinking age was not a disaster after all, nor would it likely be the case if done in the USA.

So consider this latest claim debunked.  Old enough to go to war = old enough to go to the bar.  'Nuff said.

1 comment:

  1. A drinking age of 20 had an increase in traffic crashes only because 20 was the minimum age. When the drinking age was lowered to 18, traffic crashes increased only because 18 is the minimum age. A lower drinking age doesn't contribute to an increase in irresponsible behavior. Traffic crashes are serious incidents but the drinking age in New Zealand should stay at 18. The drinking age in the U.S. should be lowered to 18. Ageists in New Zealand will misinterpret the results because they have an ageist bias against young adults.

    ReplyDelete